FUNCTIONS 5

If F(x) = 4x + 13; Find F^-1(x).

Solution

HINT: F^-1(x) means inverse.

PROCEDURE:

Make x the subject and then interchange x and y variables.

Let y=F(x)

So,  y= 4x + 13

y – 13 = 4x

y – 13  = 4x

   4          4

y – 13   = x

   4

x  =   y – 13     after rearranging

           4

F^-1(x) = x – 13    after interchanging x and y variables.

                4

Hence, F^-1(x) = x – 13     

                              4

TRY THIS………………   

If F(x) = 7x + 20; Find F^-1(x).