FUNCTIONS 4

If F(x) = 21x + 10; 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= 21x + 10

y – 10 = 21x

y – 10  = 21x

   21        21

y – 10   = x

   21

x  =   y – 10     after rearranging

           21

 y^-1 = x – 10     after interchanging x and y variables.

             21

F^-1(x) = x – 10     after interchanging x and y variables.

                21

Hence, F^-1(x) = x – 10     

                             21

TRY THIS……………………………

If F(x) = 17x + 26; Find F^-1(x).