Question Number 39204 by math khazana by abdo last updated on 03/Jul/18
$${study}\:{tbe}\:{variation}\:{of}\:{f}\left({x}\right)\:=\left(\mathrm{2}{x}+\mathrm{1}\right){ln}\left(\mathrm{1}+{e}^{−{x}} \right) \\ $$$${and}\:{give}\:{its}\:{graph} \\ $$$$\left.\mathrm{2}\right)\:{calculate}\:\:\int_{\mathrm{0}} ^{\mathrm{4}} \:{f}\left({x}\right){dx}\:. \\ $$