The function f(x) is invertible, but the function g(x)=f(cx) is not invertible. Find the sum of all possible values of c.
\(\text{Suppose $c\neq 0$}\\ y = f(c x)\\ x = \dfrac{f^{-1}(y)}{c}\\ \text{In other words for all values of $c\neq 0, g(x)$ is invertible}\\ \text{The sum of $0$ is $0$}\)
+87 
