Question

If f(x) = log2 (x + 4), what is f−1(3)?

Answer 1

t = log2 (x+4)
2^t = x+4
x = 2^t - 4

So the goal is to set f(x) equal to new variable and express x depending on that variable. that is what f-1(x) means

to find f-1(3) we have to express 3 in our new function f(t)

f(t) = 2^3 - 4 = 4