Question

Write the inverse function for the function, ƒ(x) =1/2 x + 4. Then, find the value of ƒ -1(4). Type your answers in the box

Answer 1

First find x in terms of f(x)

1/2 x = f(x) + 4
x = 2(f(x) +4)
x = 2f(x) + 8 
Now replace x by the inverse function f-1(x) and the f(x) by x

f-1(x) = 2x + 8

f-1 (4) =  2(4) + 8 = 16