Question Number 28827 by abdo imad last updated on 30/Jan/18
$${let}\:{give}\:{F}\left({x}\right)=\int_{\mathrm{0}} ^{\infty} \:\:\frac{{arctan}\left(\mathrm{1}+{x}\left(\mathrm{1}+{t}^{\mathrm{2}} \right)\right)}{\mathrm{1}+{t}^{\mathrm{2}} }{dt}\:\:{and}\:{x}>\mathrm{0} \\ $$$${calculate}\:\frac{{dF}}{{dx}}\left({x}\right).\:\: \\ $$