Question

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

Answer 1

`f(x)=2x+2\\\\ f^(-1)(x):\\ y=2x+2\\ y-2=2x\ \ \ |Divide\ by\ 2\\ (y-2)/(2)=x\\\\ f^(-1)(x)=(x-2)/(2)\\ f^(-1)(4)=(4-2)/(2)=1\\\\ Solution\ is\ f^(-1)(4)=1`

Answer 2

`f(x)=2x+2 \\\\ f(x)-1= (2*4+2)-1 \\\\ =8+2-1= \\\\ =10-1= \\\\=\boxed{9}`