Please evaluate the following integrals, using an appropriate substitution if necessary.

${\displaystyle \underset{0}{\overset{2}{}}}x\sqrt[\phantom{2}]{4-x^2}dx$

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{x^2}{(16-x^3{)}^2}dx$

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}{e}^x(1-2e^x)dx$

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{sinx}{co{s}^{4}x}dx$

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}[x^2\frac{1}{(3x{)}^2}]dx$