If

Question

g(x) = x2 + 8x
with
x ≥ −4,
find
g−1(20)

Answer 1

when does g(x)=20?
When x=2
So, g^-1(20) = 2

Note that g(-10) = 20 as well, but that does not matter, since we have restricted our domain to x >= -4.