Evaluate the following:

$6.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}4x(x^2+5{)}^{3}dx$

$7.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}8cos(4x)dx$

$8.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}{x}^3{e}^{x^4}dx$

$9.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}8x\sqrt[\phantom{2}]{40-2x^2}dx$

$10.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{x^3}{(2+x^4{)}^2}dx$

$11.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\sqrt[\phantom{2}]{5x+4}dx$

$12.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}x\sqrt[\phantom{2}]{3x^2+2}dx$

$13.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}2x\sqrt[\phantom{2}]{4x-5}dx$

$14.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(3x-4{)}^{5}dx$

$15.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\sqrt[3]{(x+2{)}^2}dx$

$16.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}{x}^3\sqrt[\phantom{2}]{1-x^4}dx$

$17.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{x^5}{(x^6-1{)}^5}dx$

$18.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{(1+\sqrt[\phantom{2}]{x}{)}^{\frac{3}{5}}}{\sqrt[\phantom{2}]{x}}dx$

$19.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{2x+1}{\sqrt[\phantom{2}]{x^2+x+1}}dx$