Mathematics for IGCSE & O level - Functions (Section 4 - No. 33)

If f(x) = 3x - 5, what is f⁻¹(7)?

4/3

16/3

First find the inverse function: y = 3x - 5 => x = (y + 5) / 3 => f⁻¹(x) = (x + 5)/3, f⁻¹(7)=(7+5)/3 = 4.