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

[tex]f(x)=2x+2\\
y=2x+2\\
2x=y-2\\
x=\frac{1}{2}y-1\\
f^{-1}(x)=\frac{1}{2}x-1\\
f^{-1}(4)=\frac{1}{2}\cdot4-1\\
f^{-1}(4)=2-1\\
f^{-1}(4)=1
[/tex]

Your answer is 1. Your welcome :)