Question

What is the inverse of the function f(x)=4x+8

Answer 1

f ( x ) − 1 = ( 1/ 4 x ) − 2.

Explanation:

For inverse function, the x and y interchanges and then make y the subject again of the equation. See the working out below:

f ( x ) = 4 x + 8

f ( x ) = y

y = 4 x + 8

x = 4 y + 8 ----- interchanging y and x

Now make y the subject of the equation:

x = 4 y + 8

− 4 y = - x + 8

y = ( − 1/ 4 ) . − x + ( − 1/ 4 ) .8

y = ( 1/ 4 x ) − 2

So the inverse function is:

f (x) − 1 = ( 1/ 4 x ) − 2