Question

For the function f(x)=5(x+10), find
f −1(x).

Answer 1

Answer: f-1(x) = x/5 - 10

Shortend: f(x)=5(x+10), f-1(x) = x/5 - 10

Steps:

The inverse can be found algebraically by switching x for y and y for x in the equation. You must then isolate y.

$f(x)=5x+10\\y=5x+10\\x=5y+10\\x-10=5y\\\frac{x-10}{5} =y$

So, $f^{-1} (x)=\frac{x-10}{5}$