FUNCTIONS 5

If F(x) = 17x + 10; Find F^-1(180).

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= 17x + 10

y – 10 = 17x

y – 10  = 17x

   17        17

y – 10   = x

   17

x  =   y – 10     after rearranging

            17

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

             17

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

                17

Then we find F^-1(180)

           F^-1(180) = 180 – 10     

                                17

           F^-1(180) = 170

                            17

           F^-1(180) = 170¹⁰

                            17

           F^-1(180) = 10

                           

TRY THIS……………………………

If F(x) = 7x + 2; Find F^-1(13).