FUNCTIONS 1

If F(x) = 2x + 20; 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= 2x + 20

y – 20 = 2x

y – 20  = 2x

   2          2

y – 20   = x

   2

x  =   y – 20     after rearranging

           2

 y^-1 = x – 20     after interchanging x and y variables.

             2

F^-1(x) = x – 20     after interchanging x and y variables.

                2

Hence, F^-1(x) = x – 20     

                             2

TRY THIS……………………………

If F(x) = 2x - 27; Find F^-1(x).