$($a$)$ Evaluate

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{e^x}{e^x+4}dx$

$($b$)$ Evaluate

${\displaystyle \underset{1}{\overset{3}{}}}\frac{e^x}{e^x+8}dx$

$($c$)$ Evaluate

${\displaystyle \underset{4}{\overset{9}{}}}\frac{4x+8}{\sqrt[\phantom{2}]{x^2+4x}}dx$