Question Number 34291 by math khazana by abdo last updated on 03/May/18
$${let}\:{B}\left({x},{y}\right)\:=\:\int_{\mathrm{0}} ^{\mathrm{1}} {u}^{{x}−\mathrm{1}} \left(\mathrm{1}−{u}\right)^{{y}−\mathrm{1}} \:{du}\:\:{and} \\ $$$$\Gamma\left({x}\right)=\:\int_{\mathrm{0}} ^{\infty} \:{t}^{{x}−\mathrm{1}} \:{e}^{−{t}} {dt} \\ $$$$\left.\mathrm{1}\right)\:{prove}\:{that}\:\Gamma\left({x}\right)\:=\:\mathrm{2}\int_{\mathrm{0}} ^{\infty} \:{u}^{\mathrm{2}{x}−\mathrm{1}} \:{e}^{−{u}^{\mathrm{2}} } {du} \\ $$$$\left.\mathrm{2}\right){give}\:\Gamma\left({x}\right)\Gamma\left({y}\right)\:{at}\:{form}\:{of}\:{double}\:{integrale} \\ $$$$\left.\mathrm{3}\right){prove}\:{that}\:{B}\left({x},{y}\right)\:=\frac{\Gamma\left({x}\right)\Gamma\left({y}\right)}{\Gamma\left({x}+{y}\right)} \\ $$$$\left.\mathrm{4}\right)\:{calculate}\:{B}\left({m},{n}\right)\:{for}\:{m}\:{and}\:{n}\:{integr}\:{naturals} \\ $$