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# How To Find Domain And Range Of A Function – Detailed Guide !!? Top 4 Best Answers

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## Domain and range of a function given a formula | Algebra II | Khan Academy

Domain and range of a function given a formula | Algebra II | Khan Academy
Domain and range of a function given a formula | Algebra II | Khan Academy

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In fact, the range and range of functions is one of the most important disciplines in mathematics, and it will eventually help you solve any problem in algebra (including graphics) or trigonometry. Using the concepts of the domain and range of each function, you can quickly find the minimum and maximum values ​​that each function can achieve exactly. In this post, we’ll explore all the different types of methods that can be used to easily find the domain and scope of a function. So relax and read on. So let’s start with the basics and step into each type of functionality (with different possible solutions). Also, later we will see some shortcuts to resolve any domain and scope issues in seconds. Time to dive into the main coverage points of this post so you can refer to them right away: What is the domain and scope of a function? How to find the domain of a function? .How to find the scope of a function? How to find the domain and scope of a function? How to find the domain and scope of a composite function? Find shortcuts for domains and scopes. Domains and realm examples are resolved. I very much hope that all the topics have been dealt with here. Don’t worry if something is missing from the list above, as we’ll be covering many sub-topics within each of the overarching topics above. Note: Before delving into this topic, it is important to understand the parentheses used to mark intervals on the number line. Always remember that when we search for domains and ranges, we mainly use two types of parentheses: 1. Parentheses (also known as parentheses) – represent values ​​excluding endpoints (points on the x-axis in an open interval) . 2. Square brackets​​—represents a value including an endpoint (a point on the x-axis in a closed interval) Example: When the range is given by the Range of f(x) = [2,5) ⇔ this means The Der Range of f(x) includes all values ​​in the interval from 2 to 5, including the value (point) “2”, excluding the point “5” on the number line, as shown in the figure below: The extreme value on the x-axis is H. The periods “infinity” and “-infinity” are never joined using square brackets, ie. H. The infinity point “∞” should not be linked with square brackets. Without wasting any more time, let’s go straight to this interesting (a bit long :-p) post.

## What Is Domain And Range Of A Function In Simple Words ?

Let us understand this in layman’s terms. Just think of a candy machine, if you insert any number of coins you will get the corresponding amount of candy from the machine. The concept is just right. Now let’s go back to our main topic. In mathematics, we are mainly concerned with different types of algebraic expressions (i.e. functions and relations). So, algebraic functions are specifically defined for a range of values, and when we substitute those values ​​into a mathematical expression, we get the value of the function. Now, let’s conser a simple function like this: f(x) = x ; the above expression is simple (isn’t it!). Now here we can say that for a function f(x), the domain can be defined as all possible values ​​of “x” in the function (for which the function f(x) is defined). And Range can be defined as all possible values ​​of f(x) we get after setting different x values. Let’s try to relate it to the candy vending machine we saw earlier. In this case, we can easily say that the coins we put into the machine are the “domain” (i.e. different values ​​of x) and the amount of candy we get back is the “range” (i.e. the value of f) (x ) is set differently the x value). The candy machine will actually act as a mathematical function f(x). To make it easier to remember, you can remember the above concept as follows: Scope of a function ⇒ input values ​​(all possible input values) Scope of a function ⇒ output values ​​(all possible output values) To further illustrate this theory, let us To understand another simple example: imagine a function: f(x) = 1/x ; (read the function as 1 dived by x) The above function is uniquely defined for all real values ​​of x in the array, but for f( x) becomes undefined, and d is the denominator not. Therefore, the domain of the function is given by the domain of the expression f(x) = R – {0} (this indicates that the domain consists entirely of real numbers, except for “0”, which makes the function undefined). There is no domain value of ‘0’) any real value in f(x), we get the range of f(x) as a real value in the number line. Therefore, the range consists of all real numbers “R”, which is H. (-∞ , ∞) is on a number line satisfying f(x). Hopefully you are now clear on the concept, what exactly is the domain and scope of a function. Now is the time to look at these two issues in more detail. Note: For simplicity, you may find the following notation helpful (as you will find it throughout this gue): ‘∈’ —> This stands for an “element” that “belongs to” (eg: x ∈ N means x belongs to all natural numbers) R —> all real numbers on the number line ‘ : ‘ —> read “this way” (eg x : x – 6 = 5 , read as x such that x – 6 = 5) a/b — > read it as a dived by b a^b —> read it as ‘a’ raised to the ‘b’ power (eg a^2 is just ‘a’ squared).

## How To Find Domain Of A Function ?

Honestly, finding the domain of a function is much simpler than finding the domain of a function. Also, you can find the domain simply by examining the math expression. So always remember the main definition of the domain of a function f(x): a domain is a well-defined set of values ​​for a function. Mathematically, we can say that the domain of a function can be defined as follows: Let f : A -> B be a function where the set A consists of a finite number of elements. Then f(x) can be described by listing the values ​​it obtains at different points in its range. Then the set A is called the domain of f. Let A = {-2 , -1 , 0 , 1 , 2} and​​ B = {0 , 1 , 2 , 3 , 4 , 5 , 6} Now conser a function f(x), written as f(x) = x is defined as ^2 (read as the square of x) Now if we take different values ​​from set A i.e. H. {-2,-1,0,1,2}, substitute into the above function, get: f(-2) = ( -2)^2 = 4 ; f(-1) = (-1)^2 = 1 ; f(0) = 0^2 = 0 ; f(1) = 1^2 = 1 ; f(2) = 2^2 = 4 ; Obviously, each element of set A is associated with a unique element of B. So here we can say that f(x) = x^2 given at f : A –> B is a function, the domain is given by: domain (f) = A = {-2 , -1 , 0 , 1 , 2} and​​ range (f) = {0,1,4} Note: Two functions f and g are consered equal if and only if: the domain of f = the domain of g f(x) = g (x) for all x belonging to their common field. Now let’s see a practical way to quickly find a domain. If needed, you can even quickly find the domain and extent of the graph. Just check out the post here.

## How To Find Domain Of A Function Algebraically ?

For simple algebraic equations, you can easily comment on the domain of the function on the basis of the below two conditions i.e. for any function  f(x) , first look for the below conditions right away : The denominator of a function should never be ‘0’ (else it will become undefined). Inse a square root, a negative value is not allowed. Except for these two conditions, the domain of any function should accept all real values of the number line i.e. ‘R‘ (this conditions mostly holds for majority cases, also in some other cases like logarithms there are some other conditions you may need to check) So just remember the above two conditions, let’s explore some important varieties of any mathematical function .

### How To Find The Domain Of A Function With A Square Root ?

As seen above, here we’ll see the application of the above two rules for finding a domain with square root function . Let the function given by : 1. f(x)    =    ; Clearly f(x) assumes real values , if we have the quantity inse the square root as positive value i.e. x – 2 ≥ 0 ⇒   x ≥ 2  ⇒ x ∈ [ 2 , ∞ ) Hence the domain of this given function is given by Domain (f) = [ 2 , ∞ )  Notice that the value ‘2’ is included and ‘∞’ has been excluded from the domain above. 2. f(x)   =    Now here we have to apply both the rules . We have to ensure the value of x such that the denominator will not become 0 and inse square root we should have a positive value. Clearly f(x) assumes real value and it is defined for values of x such that : 1 – x ≥ 0  ⇒ x ≤ 1 ⇒  x ∈ (-∞ , 1 ] , but to ensure the first condition i.e. denominator non zero , f(x) is not defined at x = 1 . Hence the final domain for f(x) is Domain f(x) = (-∞ , 1 ) in the number line .

### How To Find The Domain Of A Rational Function ?

Firstly , what is a Rational function ? . A rational function in maths basically represents a fraction form i.e. p/q form (read p dived by q form) . So a function consisting of both numerator and denominator is sa to be a rational function . So any function of the form of an algebraic fraction for example : f(x) = 2x + 3y =5  (here dinominator is ‘1’) f(x) = (4x^3 + 2x^2 + 5x + 8) / (2x^3 + 2x + 7)  is also a rational function containing numerator and dinominator both . (read the symbol ‘^’ as raised to the power) In practice we will mainly deal with the Real valued function . Now what is this this real valued functions ? A function f : A –> B is called a real-valued function, if B is a subset of R(set of all real numbers) . If Aand B both are subsets of R , then function f is called a Real function . Normally a real function is desired by giving some maths expression or formula describing it without specifying the exact domain . For eg if f(x) = 3x^4 – 5x^2 +9 , then if we want the value of f(x-1) ,           ….(read the ‘a^b’ as ‘a’ raised to ‘b’) then we must simply put the value of ‘x’ as ‘x-1’ i.e. f(x-1) = 3(x-1)^4 – 5(x-1)^2 + 9 = 3x^4 – 12x^3 + 13x^2 – 2x + 7                     …….   (on solving) Here for sake of simplicity and ease of solving we will mainly concentrate on the following forms of a rational function forms : f(x) =  quadratic/linear ;      f(x) = linear/linear ;    f(x) = linear/quadratic ;        f(x) = quadratic/quadratic   ; A quadratic equation is of the form : ax^2 + bx + c = 0 (degree of the quadratic equ should be 2 and for  linear equation the degree is 1)

### How To Solve For Domain In The Rational Function Of The Form ( linear/linear  ) ?

Now let us conser the function given by : f(x)     =      linear / linear    =     (x-1)/(x-3) Again use the same two rules given above for finding domain , (here also check for the ‘x’ value for which the denominator is becoming ‘0’ ) Clearly for x = 3 , the function is undefined , thus the domain of this real function f(x) is given as : Domain of f = R – {3}  (i.e. all real values except the value ‘3’)

### How To Solve For Domain In The Rational Function Of The Form ( Quadratic/linear  ) ?

Now let us conser the function given by : f(x) = Quadratic / linear = (x^2 – 5x + 4) / (x – 3) Again use the same two rules given above for finding domain , (here also check fo the ‘x’ value for which the denominator is becoming ‘0’ ) Clearly for x = 3 , the function is undefined , thus the domain of this real function f(x) is given as : Domain of f = R – {3}  (i.e. all real values except the value ‘3’)

### How To Solve For Domain In The Rational Function Of The Form (Quadratic/Quadratic) ?

Now let us conser the function given by : f(x) = Quadratic / Quadratic =  (x^2 + 3x + 5) / (x^2 – 3x + 2)                 ….(read the ‘a^b’ as ‘a’ raised to ‘b’) Again use the same two rules given above for finding domain , (here also check fo the ‘x’ value for which the denominator is becoming ‘0’ ) Clearly for x = 1 and x= 2 (On finding the roots of the quadratic equation present in the denominator) , the function is undefined , thus the domain of this real function f(x) is given as : Domain of f = R – {1,2}  (i.e. all real values except the value ‘1’ and ‘2’)

### How To Solve For Domain In The Rational Function Of The Form ( Linear/Quadratic  ) ?

Now let us conser the function given by : f(x) = Linear / Quadratic =   (3x + 5) / (x^2 – 5x + 4)                      ….  (read the ‘a^b’ as ‘a’ raised to ‘b’) Again use the same two rules given above for finding domain , (here also check fo the ‘x’ value for which the denominator is becoming ‘0’ ) Clearly for x = 1 and x= 4    (On finding the roots of the quadratic equation present in the denominator) , the function is undefined , thus the domain of this real function f(x) is given as : Domain of f = R – {1,4}  (i.e. all real values except the value ‘1’ and ‘2’) Finally we’ve covered all the types of rational function for finding the domain values . Now we’ll see some special type of functions where you can directly comment about the domain straight away : 1. For a constant function i.e. f(x) = k (const) for all x ∈ R , domain is simply the whole real values in the number line i.e. R . 2. For a modulus function f(x) = |x| , the domain is simply the range of all real values i.e.R. 3. For a Greatest integer function (GIF) , f(x) = [x] , the domain is simply the range of all real values i.e.R. eg of GIF , [2.85] = 2 , [-7.45] = -8 , [6.93] = 6 (this function is also called step function) 4. For a logarithmic function i.e. f(x) =   for x > 0 , now the domain of this log function is set of all non negative real numbers i.e. (0,∞) . Also remember that the value of ‘a‘ in the above log function is always a positive value and it should be not equal to ‘1’ .  (a> 0  and a ≠ 1) 5. The domain of the square root function i.e. f(x) =   is all positive values of R i.e. [0,∞) and for the cube root function f(x) =   , the domain can be given as R i.e. (-∞ , ∞) in the number line . .

## How To Find Range Of A Function ?

So far, we have seen different ways of finding the domain of any function algebraically. Now is the time to explore the steps to find out the scope of the function. Another name for “scope” is “image”. So when we say the graph of any function f(x) it means the same. To summarize the definition of the domain of arbitrary functions: the domain of an arbitrary real function of a real variable consists of all the real values ​​taken by f(x) at points in its domain. We can properly call this range the output value we get when we set different values ​​from the range of f(x). Finding the domain of a real function f(x) is a bit tricky, requiring a different approach each time a mathematical function is encountered. Having sa that, to find the domain of a given function unambiguously, we need to follow the given sequence of steps: 1. First set y = f(x) 2. Now solve the equation y = f(x) for ‘x ‘ with y is related. Now let x = Φ(y) .. (another function) 3. Find that the “x” value obtained from x = Φ(y) is real and the “y” value in the domain lies. 4. The set of y values ​​obtained in the previous step is the domain of the function f. The above steps may be confusing to you at first glance, so it is really worth skipping to the next section to give you a clear understanding of the steps. (trust me, it’s really easy).

## How To Find Domain And Range Of A Function ?

To make the above steps clear in this section, we’ll look into some easy problems here to make the concept clear . So let’s start digging into the examples straight away and find the domain and range as below: 1. f(x) = (x – 2) / (3 – x) Clearly domain of f(x) can be evaluated easily by using the two rules given at the start . Here clearly the given function is defined for all values of ‘x’ except 3 , where the denominator will become ‘0’ and f(x) becomes undefined . Now to find the range , we’ll use the four-step rule mentioned above : 1. f(x) = y 2. y   =    On solving , x(y + 1) = 3y + 2 ; Then    x   =     ; Clearly x assumes real values for all y except y = -1 . Hence range of f = R – {-1} 2. f(x)   =   (x^2 – 9) / (x – 3) Clearly domain of f(x) can be evaluated easily by using the two rules given at the start . Here clearly the given function is defined for all values of ‘x’ except 3 , where the denominator will become ‘0’ and f(x) becomes undefined . Domain of f = R – {3}      (all real values except 3 in the number line) Now to find the range , we’ll use the four-step rule mentioned above : 1. f(x) = y 2.   y    =      =      =   x + 3      (using entity a^2 – b^2 = (a+b)(a-b)  )  ; thus finally , y = x + 3  also we can say    x  =   y – 3                                                          …. (but y = f(x) not defined at x = 3) It follows from the above relation that y takes all real values except 6 when x takes values in the set R – {3}  . If y assumes value ‘6’ , then x will result into ‘3’ which makes the f(x) undefined . Thus the range of f(x) = R – {6} Note : The four-step rule can sometimes lead to complex calculations and it becomes tough to express f(x) in terms of ‘y’ . At that time you may even use common sense to comment on the range of the function . Let’s try one by inspection : f(x)    =      Clearly the domain of the above function is R as we can put any value of x to get different values of f(x) . In the denominator, we can no way make it 0 (isn’t it !) . Now to find the range , just observe the function carefully : f(x)    =    in the numerator and denominator, we have two square terms which always results in the same value for f(x) (when we put any value for ‘x’) So let’s find out the min value of the expression by putting x = 0 (we put x = 0 as we already know the expression will result in a positive value always) On putting x = 0 , min value of f(x) = 0 we get . Now in the numerator and denominator, we can see square terms , which further make us conclude that the max value will never attain ‘1’ . for eg , put x = 2 , x = 5 , x = 7 etc , always an extra ‘1’ will be added in the denominator which eventually make the f(x) value close to ‘1’ and not exact ‘1’ Thus ,we can conclude that the range of f = [0,1) In this way, we can find the range by using some different approaches and accomplish our mission of finding a range of f(x) . Now its time to see some complex rational functions and the way to find its range and domain systematically.

### How To Find Domain And Range Of A Rational Function Of The Form (Linear/Quadratic) ?

Conser the below function f(x) , and let’s find out the range and domain :     f(x)     =    The domain of the above function is clearly R i.e. (-∞ , ∞)  in the number line . (in other words there is no value where the function will become undefined) Now its time to find the range of f(x) by the four-step rule mentioned above : 1. Let y = f(x) 2. Now we have to express f(x) in terms of y y   =  Then ,       y + yx^2 = x ; Also  ,      yx^2  – x + y = 0 Now this is a quadratic equation of the form   :  ax^2 + bx + c = 0 where a = y , b = -1 , c= y Now we know the roof of any quadratic equ is given by x   =  Putting the values of a, b ,c above , we get : x     =          …(D ≥ 0 for real roots) On solving the above equations , we will get the two roots . But we are interested in the domain where the value of ‘x’ is possible . So our main concentration should be inse the square root , which should be a positive term . (also the denominator should not be zero i.e. y ≠ 0  ) Then ,     1 – 4y^2 ≥ 0 ;   On solving , (y – 1/2)(y + 1/2)  ≤ 0             …….  (we know Inequality sign changes on multiplying with ‘-‘ sign throughout the equ) now lets plot this on the number line as below : y ∈  [-1/2 , 1/2]  (we’ve used square brackets as we have an inequality with the ‘equal’sign) and also y ≠ 0 (as the denominator should not be zero) Now we get the range of values for which ‘x’ is defined , now let’s compare this values with the actual equation of y = f(x) , So as per this , f(x) will never become ‘0’ on any value of ‘x’  so if we put x = 0  then value of f(x) is becoming ‘0’ f(x)     =       ; f(0) = 0 / (0+1) = 0    ;    This simple states that the condition y ≠ 0 is not val (condition) and should not be included as the range of f(x) (because we are getting range of f(x) as ‘o’ for the value  x = o ) . Thus the final result is that the domain of f is R and range of f = y ∈  [-1/2 , 1/2]

## How To Find Domain And Range Of A Composite Function ?

What do we mean by composite functions ? So a composite function basically consists of more than one function being operated upon by various mathematical operations (like a simple add , subtract , product or division) . Till now we have seen the method to find the domain and range of a single function at a time . Now here we’ll deal with say two separate functions f(x) and g(x) with different domains and range values . Firstly we will see a simple problem containing function of functions , then eventually we’ll proceed further with the different operations based on functions . Conser two functions as f(x) = 3x – 12 and g(x) = √x , Now find the domain and range for the following functions as given below : 1. f(g(x))     And    2. g(f(x)) 1. First we need to find the domain and range of f(g(x)) This simply means that we need to put the value of the function g(x) in the place of ‘x’ and find the final function f(x) as shown below : Since g(x) = √x , Now f(g(x))  =   f(√x)  =  3√x  – 12  —->  This is our final function ,that we need to evaluate for domain and range . Clearly domain of the function f(g(x)) =  3√x  – 12 is  all positive R values including ‘0’ i.e. [0,∞) Hence the domain of f(g(x)) is  { x ≥ 0 | x ∈ R } Now range can be calculated as just by inspection i.e. for the minimum value of x in it’s domain , f(g(x)) gives value as ‘-12’ ( since the min value that x can take is ‘0’ , by putting this in the function we get min value of the range as ‘-12’) And the max value it can take is ‘∞’ , so the max value of the function f(g(x))  will be ‘∞’  .  (since it is a polynomial function) Range of the function f(g(x))  is { y ≥ -12 | y ∈ R }                  ……. where y = f(g(x)) 2. First, we need to find the domain and range of g(f(x)) This simply means that we need to put the value of the function f(x) in the place of ‘x’ and find the final function g(x) as shown below : Since f(x) = 3x – 12 , Now  g(f(x))  =   g(3x-12)  =  √(3x-12)  —->  This is our final function ,that we need to evaluate for domain and range . Clearly domain of the function g(f(x)) = √(3x-12)   is  : 3x – 12 ≥ 0 ;        (anything inse root should be positive) Thus ,  the domain will be x ≥ 4  or  x ∈ [4 , ∞) Hence the domain of g(f(x)) is  { x ≥ 4 | x ∈ R } Now range can be calculated as just by inspection i.e. for the minimum value of x in it’s domain , g(f(x)) gives value as ‘0’ ( since the min value that x can take is ‘4’ , by putting this in the function we get min value of the range as ‘0’) And the max value it can take is ‘∞’ , so the max value of the function g(f(x))  will be ‘∞’  .  (since it is a polynomial function) Range of the function g(f(x))  is { y ≥ 0 | y ∈ R }                  ……. where y = g(f(x)) Note : The sum , difference , product, and quotient are defined for real functions only on their common domain . Thus for example , if we have the addition operation to be performed , we can say that : Let f : D1 –> R and g : D2 –> R be two real functions . Then their sum f + g is defined as that function from D1 ∩ D2 to R which associates each x ∈ D1 ∩ D2 to the number f(x) + g(x) Here D1 and D2 are the domains of the function f(x) and g(x) respectively . Thus we can say that : (f+g)(x) = f(x) + g(x) for all x ∈ D1 ∩ D2 ; Likewise for subtract, product, quotient  operation, we can define in a similar manner : (f * g) (x) = f(x) g(x)  for all x ∈ D1 ∩ D2  ; (f – g) (x) = f(x) – g(x) for all x ∈ D1 ∩ D2  ; (f/g) (x) = f(x) / g(x)  for all x ∈ D1 ∩ D2  – {x : g(x) =0} On multiplication of a function by a scalar (real number say ‘α’) : (αf)(x) = α f(x)  for all x ∈ D Now lets try out a simple problem based on this composite real functions to make this concept clear : Let f and g be two real functions defined by : f(x) = 1/(x+4)    and    g(x) = (x+4)^3 Find the following : 1. f + g            2. f – g              3. f*g             4. f/g              5. 1/f            6. 1/g          7. 2f Firstly we need to find their common domain (operation on real functions is defined only on their common domain as stated earlier) Clearly for the function  f(x)  =  1/(x+4)  , this is defined for values of x except x = -4 (at which denominator will become ‘0’) Domain of f = R – {-4}      (all real values except ‘-4’ ) Now for the next function g(x) = (x+4)^3      , clearly this is defined for all values of ‘x’ which make us to conclude its domain as : Domain of g = R  ( i.e. g(x) is defined for all values of x ∈ R) Now their common domain D1 ∩ D2 is given by Domain of (f) ∩ Domain of (g) = R – {-4} 1. (f+g)(x) = f(x) + g(x) for all x ∈ D1 ∩ D2 (f+g)(x)   =   1/(x+4)  +  (x+4)^3    =  2. (f-g)(x) = f(x) – g(x) for all x ∈ D1 ∩ D2 (f-g)(x)   =   1/(x+4)  –  (x+4)^3    =  3. (f.g) (x) = f(x) g(x)  for all x ∈ D1 ∩ D2  ; (f.g)(x) = f(x) . g(x)  =  (x+4)^2 4. (f/g) (x) = f(x) / g(x)  for all x ∈ D1 ∩ D2  – {x : g(x) =0} f(x)/g(x)  =  1/ (x+4)^4    for all x ∈ R – {-4} 5. (1/f)(x) = 1/(f(x)) = x+4 6. (1/g)(x) = 1/(g(x)) =  1/(x+4)^3  for all x ∈ R – {-4} 7. (2f)(x) = 2 (f(x)) = 2/(x+4)  for all x ∈ R – {-4} In the next section we’ll further see some useful tricks to solve the domain and range problems of certain type quickly . So let’s proceed further . Shortcut Tricks To Find Domain And Range Of A Function   !! The methods we’ll discuss here are not exactly shortcuts , these are some proven techniques that you may use to get the results fast  (conser these as just some time-saving methods). Firstly let us see the domain and range of basic trigonometric functions (keep them handy always) :   Trigonometric Function                Domain                Range         Sine Function (sinθ)                  θ  ∈  R                   [-1,1]        Cosine Function (cosθ)                  θ  ∈  R                   [-1,1]       Tangent Function (tanθ)   θ  ∈  R  – {(2n+1) x 90°}                   [-∞,∞] Now with this knowledge, we can directly use this to predict the domain and range of any function including the trigonometric functions. Let’s see some applications : It is very much event from the above that the domain is always ‘R’  for these trigonometric functions , so we’ll mainly concentrate on finding the range . Shortcut tip 1 : If the function is given in the form  : f(x)  =    in place of  sinθ and cosecθ , we can also have any other reciprocal combinations like (tanθ , cotθ) and (cosθ , secθ) So two conditions before you use this shortcut : 1. Both the trigonometric function should have the same angle 2. The trigonometric function should include a reciprocal pair and both should be in the square form 3. There should be a ‘+’  in between both the terms (addition) If these three conditions satisfied, then we can directly say that the min and max value of the range as : Min value of f(x) = 2√(ab)      and      max value of f(x) = always infinity (∞) This will be clear on solving the below examples. Find the range (min and max values) for the below functions : 1. f(θ)   =    Clearly the angle is the same in both the trigonometric terms i.e. theta and also both the terms are reciprocal of each other (sin and cosec)  and also a ‘+’ sign in between. Applying the formula : Min value of the range : 2√(ab)  =  2√(3*4)   =   2√12  =  4√3 Max value is infinity The range is given as :   Range of  f(θ) = [4√3 , ∞) 2  f(x)  =  Clearly the angle is the same in both the trigonometric terms i.e. 2x  and also both the terms are reciprocal of each other (cos and sec)  and also a ‘+‘ sign in between . Applying the formula : Min value of the range :   2√(ab)  =  2√(9*16)   =   2√144  =  24 Max value is infinity The range is given as :   Range of  f(x) = [24 , ∞) Shortcut tip 2 : This method will only include sine and cosine terms , lets see if a function given in the form as : f(x) = asinx + bcosx        ……. (a , b can be a positive or negative integer i.e. their sign doesn’t matter) then the min and max value of the range will vary from Min value = -√(a^2 + b^2)              Max value =  √(a^2 + b^2) Range can be given as =  [-√(a^2 + b^2)  ,  √(a^2 + b^2)]                 …. (in closed interval) Conditions to be checked for this method : 1. For both the sine and cosine terms , angle should be the same 2. There should not be any different domains given for each sine and cosine terms . (there should not be any different domain for each) Note : Here , in the function, if we have different signs of ‘a’ and ‘b’ , then also the formula is val as we have square terms in the formula. Find the range for the function : 1. 3sin4x – 4cos4x Clearly the angle is same,  and no specific domain mentioned. So we’ll directly use the above method . here a = 3 and b = -4 Min value is = -√(a^2 + b^2) = -√(3^2 + (-4)^2)  = -5    ; Max value of f(x) = √(a^2 + b^2) =  √(3^2 + 4^2) = 5     ; Range of f(x) =  [-5,5] 2.    -4cos5x – 3sin5x  – 5 Here we have the function as :  f(x)  =  -4cos5x – 3sin5x  – 5 let assume ,     g(x)  = -4cos5x – 3sin5x   , such that f(x)  =  g(x)  – 5 Min value of g(x) =  -√(a^2 + b^2)  =   -√(3^2 + 4^2)   =    -5 Max value of f(x) = √(a^2 + b^2) =  √(3^2 + 4^2) = 5 Range of g(x)  =  [-5,5] Now we have f(x) = g(x) – 5 Range of f(x)  =  [-5  – 5 ,5 –  5]   =   [-10 , 0] 3. Shortcut tip 3 : We already know the range of basic trigonometric functions i.e. sine , cosine, and tangent functions . So we can easily apply this logic in solving other functions involving these trigonometric functions . Find the range for the function : f(x) =  4sinx + 6          Now here we have a function including a trigonometric function sinx , as we already know that the range of a sine function varies in between  -1 to 1 i.e.       Range of sinx =      -1   ≤ sinx  ≤   1   ; But we want the range for the function i.e.   4sinx + 6 , for this we need to transform the above inequality condition satisfying the given function : We have :    – 1   ≤ sinx  ≤   1     ; Now multiplying with 4 throughout this equation ,  i.e.       – 4   ≤  4sinx  ≤   4                …….( no affect on the inequality sign-on multiplying with a constant value )   Now , adding ‘6’ through the equation :  i.e.      – 4  +  6   ≤  4sinx  + 6   ≤   4 + 6    This implies :    2   ≤ 4sinx  + 6 ≤   10 Finally we get the range of the f(x)   as     [2,10] Similarly, we can evaluate functions involving cosine and tangent functions.   .

## How To Find Domain And Range Of A Function Using AM and GM Method ?

For AM and GM we basically mean the arithmetic mean or geometric mean. So far, we have used traditional methods to find the domain and scope of each function. However, using AM and GM, we can quickly find the min/max of the function. First let us understand what AM and GM are, let a and b be two positive integers, then AM = (a + b)/2 and GM = √(ab​​) and the condition is always true, i.e. H. AM ≥ GM Also, if we have three integers, then AM = (a + b + c)/3 and GM = (abc)^(1/3) . (read ‘a’b’ as ‘a’b ‘ increases to ‘b’) so AM and GM work for any number of positive integers. So the main condition before applying this logic is to check if the number is positive. We also need to check for equality to find the “x” value where the two functions are equal. If there is no value, we cannot apply this logic. Hint: The two functions should be inverses of each other so that they cancel each other out and produce a constant value within the square root. Let’s find the domain of the function f(x) = So now how do we check if AM and GM logic can be applied here? Here we have two parts in the function f(x) d. H. a = x^2 and b = 4/(x^2) Again, both parts are positive. And the two parts are mutual (ignore the constant ‘4’ for now). Therefore, we can apply the AM and GM methods here as follows: AM ≥ GM ⇒ (a + b) /2 ≥ √(ab​​) So we can write: (a + b) ≥ 2√(ab). ​For a and b above, we get ≥ 2 √ [x^2 * (4/x^2)] So, , ≥ 2 * 2 or 4 Now we can say that the function f(x’) has a minimum value of 4 ‘, to confirm this, we need to check the equality point of ‘x’ Now let’s make a and b equal, which is H. a = b x^2 = 4/x^2,.. .. (read ‘a^b’ as ‘a’ to increase ‘b’) Now, x^4 = 4 these two work, you’re in where the work is the same. So now we can say that the value ‘4’ is the minimum value of the f(x) range. Now let the maximum value x = ∞ , , , then we get f(x) = ∞ + 4/∞ = = ∞ so the maximum value of f(x) is infinity. Finally we can say that f(x) is in the range [4,∞) . Also, we can use trigonometric functions that are inverses of each other in place of “x”, such as for (sine, cosec) or (cosine, sec) etc., then we can use this AM and GM trick to find the range of find out of f(x) .

## Miscellaneous Solved Examples Of Domain And Range Of A Function !!

We’ve seen many different types of examples so far. Let’s continue this tradition and try out some different types of functions to give you an insight into the different ways to find domains and ranges. Let’s find the domain of the function: f(x) = ; here we have an inverse trigonometric function, we now know that ‘x’ is defined for all values ​​of ‘x’ ranging from [-1,1] which means, , -1 ≤ x ≤ 1 , but here we have, x ^2 – 3 inches of ‘x’ space, ie: -1 ≤ x^2 ​​– 3 ≤ 1 , now we have two functions as follows: x^2 – 3 ≥ -1 and x^2 – 3 ≤ – 1 Now we need to find the common value of “x” that satisfies both functions. f1(x) = x^2 – 3 ≥ -1 ; i.e. x^2 – 2 ≥ 0 or (x + √2)(x – √2) ≥ 0 in the domain = (-∞ , -√2] ∪ [ √2 , ∞ ) f2(x) = x^2 – 3≤-1; when solving, (x + 2)(x – 2) ≤ 0 domain = [-2,2] Now we need to find the The common domain of these two equations (the values ​​of x satisfy eq) let us get the common value of ‘x’ as follows: Domain of f1(x) ∩ Domain of f2(x) = [-2 , -√2] ∪ [ √2 , 2] 2. Find the domain of the function: f(x ) = Here we have a modulo function and a square root function as the denominator. Therefore, the function is uniquely defined for all x , except for values ​​whose denominator becomes “0”. Now to find the domain, we can say that the following conditions should be met: |x| – x > 0 .. (the equals sign is inval because f(x) becomes undefined) Now we have, |x| > x Now let x = 0, we have 0 > 0 which is impossible now set x = 1, then 1 > 1, which is impossible now finally set x = -1, then 1 > -1 which is correct finally , we can conclude that the domain of f(x) is only defined for negative values ​​of ‘x’. Domain of f(x) = (-∞ , 0) Let me know if you want more examples on this topic. Practice is the key here. Let me know in the comments section if you have any questions. Last but not least, we can easily solve domain and range problems using graphical methods. Stay tuned for more interesting content in this series. report this ad

## How do you find the domain and range of a function?

To find the domain and range, we simply solve the equation y = f(x) to determine the values of the independent variable x and obtain the domain. To calculate the range of the function, we simply express x as x=g(y) and then find the domain of g(y).

## How do you find domain and range of a function on a graph?

Another way to identify the domain and range of functions is by using graphs. Because the domain refers to the set of possible input values, the domain of a graph consists of all the input values shown on the x-axis. The range is the set of possible output values, which are shown on the y-axis.

## How do you find the domain of a function step by step?

A function with a fraction with a variable in the denominator. To find the domain of this type of function, set the bottom equal to zero and exclude the x value you find when you solve the equation. A function with a variable inside a radical sign.

## How do I find the range of a function?

Overall, the steps for algebraically finding the range of a function are:
1. Write down y=f(x) and then solve the equation for x, giving something of the form x=g(y).
2. Find the domain of g(y), and this will be the range of f(x). …
3. If you can’t seem to solve for x, then try graphing the function to find the range.

## How do you find the domain and range of a function without graphing?

HOW TO FIND DOMAIN AND RANGE OF A FUNCTION WITHOUT GRAPHING
1. Step 1 : Put y = f(x)
2. Step 2 : Solve the equation y = f(x) for x in terms of y. …
3. Step 3 : Find the values of y for which the values of x, obtained from x = g(y) are real and its domain of f.
4. Step 4 :

## What is domain and range example?

Example 2:

The domain is the set of x -coordinates, {0,1,2} , and the range is the set of y -coordinates, {7,8,9,10} .

## What is domain and range PDF?

Domain & Range of Functions. → The domain of a function is the set of all the numbers you can substitute into the function (x- values). The range of a function is the set of all the numbers you can get out of the function (y- values).

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