Finding $u$ and $d u$ In Exercises $1-4,$ complete the table by identifying $u$ and $d u$ for the integral.
$$
\begin{array}{l}{\int f(g(x)) g^{\prime}(x) d x \quad u=g(x) \quad d u=g^{\prime}(x) d x} \\ {\int\left(8 x^{2}+1\right)^{2}(16 x) d x}\end{array}
$$