CPM Homework Help : PC3 Problem 2-146

Use composition to verify $f(x)=\frac{x^3}{7}+2$ and $g(x) =\sqrt [ 3 ] { 7 x - 14 }$ are inverse functions.

Step:

$f(g(x))=\frac{\sqrt[3]{7x-14}^3}{7}+2$

Does this composition equal $x$ ?
Be sure to verify the inverse functions using $g(f(x))$ as well.