Thursday 11 February 2016

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).

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