FUNCTIONS C3

If F(x) = 8x + 3; 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= 8x + 3

y – 3 = 8x

y – 3 = 8x

   8        8

y – 3 = x

   8

x  =   y – 3     after rearranging

           8

 y^-1 = x – 3     after interchanging x and y variables.

             8

F^-1(x) = x – 3     after interchanging x and y variables.

                8

Hence, F^-1(x) = x – 3     

                              8

TRY THIS……………………………

If F(x) = 5x + 9; Find F^-1(x).