Question

Given f(x) = 5x + 1 divided by 2, solve for f^-1(8).

O a
3
O b
7
О c
10
O d
20

Answer 1

3

Explanation:

Given the function f(x) = (5x+1)/2

We are to find the inverse first as shown;

let y = f(x)

y = (5x+1)/2

Replace y with x

x = (5y+1)/2

Make y the subject of the formula;

2x = 5y+1

5y = 2x-1

y = (2x-1)/5

f^-1(x) = (2x-1)/5

f^-1(8) = 2(8)-1/5

f^-1(8) = 16-1/5

f^-1(8) = 15/5

f^-1(8) = 3

Hence the answer is 3