FUNCTIONS 3

If F(x) = 12x + 8; 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= 12x + 8

y – 8 = 12x

y – 8  = 12x

 12        12

y – 8   = x

   12

x  =   y – 8     after rearranging

            12

 y^-1 = x – 8     after interchanging x and y variables.

            12

F^-1(x) = x – 8     after interchanging x and y variables.

                12

Hence, F^-1(x) = x – 8     

                              12

TRY THIS……………………………

If F(x) = 5x + 22; Find F^-1(x).