Inverse Functions

 

In a Nut Shell:  You can think of inverse functions as two functions with one reversing

the action of the other.  An analogy is multiplication and division in algebra. Note:  Not

all functions have an inverse.

 

Guidelines for inverse functions

 

If      x1     x2    implies that   f(x1)     f(x2)  , then  f(x) is said to be one-to-one.

 

An example of a one-on-one function is the following function,

f(x)  =  y  =  1/x   for  x > 0  For each value of x, there is only one value of y(x).

 

                                      

a.  Also if    f(x)   is one-to-one, then it has an inverse function,   f -1(x).

b.  If  g  is the inverse of  f, then  f  is the inverse of  g.

c.  The domain of  f -1  is equal to the range of  f  and the range of  f -1  is equal to the

     domain of   f.

d.  A function need not have an inverse, but if it does, the inverse function is unique.

 

 

    Strategy to find the inverse function of a one-to-one function, f.

 

 

     Switch the variables    x  and  y

 

 

             Solve for   y  in  terms of x  (if possible)

 

 

The resulting equation is     f ˗ 1 (x)  =  y

 

 

Click here for some examples.

 

Click here for information on implicit differentiation.

 


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