$4\mathrm{.}6$ Are

$19.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(x^2+1{)}^{2}dx($See Example $4.)$

$20.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}x(x^2+1{)}^{2}dx$

$21.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(1-x^2{)}^{2}xdx$

$22.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(1-x^2{)}^{2}dx$

$24.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{1+\sqrt[\phantom{2}]{W}}{\sqrt[\phantom{2}]{W}}dW$

$26.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(x^3+6{)}^2(3x^2)dx$

$28.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(3-2x^3{)}^2(-6x)dx$

$30.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(4z^3-1{)}^2(10z^2)dz$

$32.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(1-2x^2{)}^3(-4x)dx$

$34.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(1-2x^2{)}^3(x)dx$

$36.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(x^4+2{)}^2(4x)dx$

$38.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(x^3+1{)}^2{x}^{2}dx$

$40.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(3-s^4{)}^2{s}^{2}ds$

$42.{\displaystyle \underset{0}{\overset{2}{}}}(2x-1)dx$

$44.{\displaystyle \underset{1}{\overset{4}{}}}2\sqrt[\phantom{2}]{x}dx$

$46.{\displaystyle \underset{1}{\overset{6}{}}}\sqrt[\phantom{2}]{x+3}dx$

$29.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(4V^3-1{)}^2(12V)dV$

$48.{\displaystyle \underset{0}{\overset{2}{}}}\frac{x^2+2}{2}dx$

$31.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(1+x^3{)}^4(3x^2)dx$

$33.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(1+x^3{)}^4(x^2)dx$

$35.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(x^4+2{)}^2(4x^3)dx$

$37.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(x^3+1{)}^{2}xdx$

$39.{\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(3-t^4{)}^2{t}^{3}dt$

$50.{\displaystyle \underset{-2}{\overset{1}{}}}\frac{dx}{\sqrt[\phantom{2}]{2-x}}$

$52.{\displaystyle \underset{0}{\overset{1}{}}}r\sqrt[\phantom{2}]{1-r^2}dr$

$54.{\displaystyle \underset{0}{\overset{4}{}}}(2+\sqrt[\phantom{2}]{z}{)}^{2}dz$

$56.{\displaystyle \underset{1}{\overset{3}{}}}w\sqrt[\phantom{2}]{w^2-1}dw$