Question

Let f(x) = 2x +2. solve f -1 (x) when x = 4

Answer 1

If y = f(x), then f⁻¹(y) = x.

We have f(x) = 2x + 2, so that f(x) = 4 when

2x + 2 = 4

2x = 2

x = 1

So we know f(1) = 4.

Then this means 1 = f⁻¹(4).