Question

If f(x) and f^1(x)

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

-1
3/2
41/8
23

Answer 1

3/2

Explanation:

f(x) = 2x+5

f-¹(x) = ?

to find f-¹(x)

let f(x) be y

y = 2x+5

then we'll make x the subject of formula

y-5 = 2x

x = y-5/2

change y to x and x to y

f-¹(x) = x-5/2

f-¹(8) = 8-5/2 = 3/2