Question

For the function f, of, x, equals, 2, left parenthesis, x, plus, 10, right parenthesisf(x)=2(x+10), find f, to the power minus 1 , left parenthesis, x, right parenthesisf
−1
(x)

Answer 1

Let y = f(x) = 2(x + 10). Swap x and y: x = 2(y + 10). Solve for y:
x = 2y + 20 ⇒ 2y = x - 20 ⇒ y = (x - 20)/2 = x/2 - 10.

Thus f⁻¹(x) = x/2 - 10 (domain: all real numbers).