Thursday 31 March 2016

FUNCTIONS-1


If F(x) = 2x + 6; 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 + 6

y – 6 = 2x

y – 6  = 2x
  2        2

y – 6   = x
   2

x  =   y – 6     after rearranging
            2

 y-1 = x – 6     after interchanging x and y variables.
            2

F-1(x) = x – 6     after interchanging x and y variables.
               2

Hence, F-1(x) = x – 6     
                            2


TRY THIS……………………………

If F(x) = 3x + 10; Find F-1(x).


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