Answer
(a) $\int x^{2} \sqrt (x^{3} +1)$
(b)$\int tan(3x) dx$
Work Step by Step
It would be better to choose those integrals since they can both be solved through the substitution method and the procedure would be shorter and easier. In the case (a) its only necessary to substitute $ u = x^{3} +1 $. and in (b) $u=3x $.
