Question

If f(x) and f–1(x) are inverse functions of each other and mc005-1.jpg, what is f–1(8)?

Answer 1

The options for this question are missing: Here are the options:

A) -1

B) 3/2

C) 41/8

D) 23

Solution:

given  

f(X) = y = 2x+5  

(y-5)/2 = X

now replace X and y  

(x-5)/2 = y  

now this y = f^-1(X)  

so f-1(8) = (8-5)/2 = 3/2 = 1.5