W$3.$ Consider the integral ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(\sqrt[\phantom{2}]{2x+1})dx.$

$($a$)$ Find the integral using the substitution $u=2x+1.$

$($b$)$ Find the integral using the substitution $u=\sqrt[\phantom{2}]{2x+1}.($Hint: write $d\frac{u}{d}x$ in terms of $u.)$