FUNCTIONS - 1

If F(x) = 12x - 6; Find F^-1(4).

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 - 6

y + 6 = 12x

y + 6  = 12x

 12        12

y + 6   = x

   12

x  =   y + 6     after rearranging

            12

 y^-1 = x + 6     after interchanging x and y variables.

            12

F^-1(x) = x + 6     after interchanging x and y variables.

               12

F^-1(114) = 114 + 6     

                   12

F^-1(114) =  120     

                  12

F^-1(114) =  10     ANSWER

                 

TRY THIS……………………………

If F(x) = 5x + 2; Find F^-1(3).