Question

How to show these 2 problems are inverses

Answer 1

$\bf \begin{cases} f(x)=\sqrt[3]{7x-2}\\\\ g(x)=\cfrac{x^3+2}{7} \end{cases}\\\\ -----------------------------\\\\ now \\\\ f[\ g(x)\ ]\implies f\left[ \frac{x^3+2}{7} \right]\implies \sqrt[3]{7\left[ \frac{x^3+2}{7} \right]-2}\implies \sqrt[3]{x^3+2-2} \\\\\\ \sqrt[3]{x^3}\implies x\\\\ -----------------------------\\\\ or \\\\ g[\ f(x)\ ]\implies g\left[\sqrt[3]{7x-2}\right]\implies \cfrac{\left[\sqrt[3]{7x-2}\right]^3+2}{7} \\\\\\ \cfrac{7x-2+2}{7}\implies \cfrac{7x}{7}\implies x$

thus f[ g(x) ] = x indeed, or g[ f(x) ] =x, thus they're indeed inverse of each other