Question

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

Answer 1

Answer:

$f^{-1}(x) = \frac{1}{12}(x+20)$

Step-by-step 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

∴ $\frac{1}{12} (y+20) = x$

Replace the places of x and y.

∴ $y=\frac{1}{12} (x+20)$

∴ $f^{-1}(x) = \frac{1}{12}(x+20)$