Question

If f(x) and 1(x) are inverse functions of each other and f(x) = 2x + 5, what is f^-1(8)?

A. - 1
B. 3/2
C. 41/8
D. 23​

Answer 1

Answer: B

Explanation:

To solve this problem, we first need to find the inverse of f(x). Then, you would plug in x=8. To find teh inverse, you switch y with x and x with y, then solve for y.

y=2x+5 [switch y with x and x with y]

x=2y+5 [subtract both sides by 5]

x-5=2y [divide both sides by 2]

y=(x-5)/2

Now that we have the inverse function, we plug in x=8 and solve.

y=(8-5)/2 [subtract]

y=3/2

Now, we know that f⁻¹(8)=3/2.