Question

If f(x) = 4(3x - 5), find f-1(x)

Answer 1

`f^(-1)(x) = (1)/(12)(x+20)`

Explanation:

Given: f(x) = 4(3x - 5)

Is required to find f⁻¹(x)

f(x) = y = 4(3x - 5)

∴ y = 4 * 3x - 4 * 5

∴ y = 12x - 20 ⇒ add 20 to both sides

∴ y + 20 = 12x ⇒ divide both sides by 12

∴
`(1)/(12) (y+20) = x`

Replace the places of x and y.

∴
`y=(1)/(12) (x+20)`

∴
`f^(-1)(x) = (1)/(12)(x+20)`