there's more than one way to combine them really
but an obvious one will be
[tex]\bf \begin{array}{llll}
h(x)&=&(f\circ g)(x)\\\\
&&\sqrt[3]{7x+1}\\\\
&&\sqrt[3]{g(x)}\leftarrow
\begin{array}{llll}
f(x)=\sqrt[3]{x }\\\\
g(x)=7x+1
\end{array}
\end{array}\\\\
-----------------------------\\\\
(f\circ g)(x)\iff f[\quad g(x)\quad ]=\sqrt[3]{g(x)}\implies f[\quad g(x)\quad ]=\sqrt[3]{7x+1}[/tex]