Question Number 116361 by mohammad17 last updated on 03/Oct/20 | ||
Commented by mohammad17 last updated on 03/Oct/20 | ||
$${prove}\:{that} \\ $$ | ||
Answered by maths mind last updated on 05/Oct/20 | ||
$$\int\frac{{e}^{{x}} {ln}\left({x}\right)}{{x}}{dx} \\ $$$${by}\:{part}\:{u}'=\frac{{e}^{{x}} }{{x}},{v}={ln}\left({x}\right),{u}={Ei}\left({x}\right),{v}'=\frac{\mathrm{1}}{{x}} \\ $$$$\int\frac{{e}^{{x}} {ln}\left({x}\right)}{{x}}{dx}={Ei}\left({x}\right){ln}\left({x}\right)−\int\frac{{Ei}\left({x}\right)}{{x}}{dx} \\ $$$${Ei}\left({x}\right)=\gamma+{ln}\left({x}\right)+\underset{{k}\geqslant\mathrm{1}} {\sum}\frac{{x}^{{k}} }{{k}.{k}!} \\ $$$$\int\frac{{e}^{{x}} {ln}\left({x}\right)}{{x}}{dx}={Ei}\left({x}\right){ln}\left({x}\right)−\int\frac{\mathrm{1}}{{x}}\left(\gamma+{ln}\left({x}\right)+\underset{{k}\geqslant\mathrm{1}} {\sum}\frac{{x}^{{k}} }{{k}.{k}!}\right){dx} \\ $$$$={Ei}\left({x}\right){ln}\left({x}\right)−\int\frac{\gamma}{{x}}{dx}−\int\frac{{ln}\left({x}\right)}{{x}}{dx}−\underset{{k}\geqslant\mathrm{1}} {\sum}\int\frac{{x}^{{k}−\mathrm{1}} }{{k}.{k}!}{dx} \\ $$$$={Ei}\left({x}\right){ln}\left({x}\right)−\gamma{ln}\left({x}\right)−\frac{{ln}^{\mathrm{2}} \left({x}\right)}{\mathrm{2}}−\underset{{k}\geqslant\mathrm{0}} {\sum}\int\frac{{x}^{{k}} }{\left({k}+\mathrm{1}\right)\left({k}+\mathrm{1}\right)!}{dx} \\ $$$$={Ei}\left({x}\right){ln}\left({x}\right)−\gamma{ln}\left({x}\right)−\frac{{ln}^{\mathrm{2}} \left({x}\right)}{\mathrm{2}}−\underset{{k}\geqslant\mathrm{0}} {\sum}\frac{{x}^{{k}+\mathrm{1}} }{\left({k}+\mathrm{1}\right)^{\mathrm{2}} \left({k}+\mathrm{1}\right)!}+{c} \\ $$$$\underset{{k}\geqslant\mathrm{0}} {\sum}\frac{{x}^{{k}+\mathrm{1}} }{\left({k}+\mathrm{1}\right)^{\mathrm{2}} \left({k}+\mathrm{1}\right)!}=\underset{{k}\geqslant\mathrm{0}} {\sum}\frac{{k}!.{k}!.{k}!}{\left({k}+\mathrm{1}\right)^{\mathrm{2}} \left({k}+\mathrm{1}\right)!.{k}!.{k}!}.\frac{{x}^{{k}+\mathrm{1}} }{{k}!} \\ $$$$={x}\underset{{k}\geqslant\mathrm{0}} {\sum}\frac{{k}!.{k}!.{k}!}{\left({k}+\mathrm{1}\right)!\left({k}+\mathrm{1}\right)!\left({k}+\mathrm{1}\right)!}\frac{{x}^{{k}} }{{k}!} \\ $$$${k}!=\left(\mathrm{1}\right)_{{k}} ,\left({k}+\mathrm{1}\right)!=\left(\mathrm{2}\right)_{{k}} \\ $$$$={x}\underset{{k}\geqslant\mathrm{0}} {\sum}\frac{\left(\mathrm{1}\right)_{{k}} \left(\mathrm{1}\right)_{{k}} \left(\mathrm{1}\right)_{{k}} }{\left(\mathrm{2}\right)_{{k}} \left(\mathrm{2}\right)_{{k}} \left(\mathrm{2}\right)_{{k}} }.\frac{{x}^{{k}} }{{k}!}={x}_{\mathrm{3}} {F}_{\mathrm{3}} \left(\mathrm{1},\mathrm{1},\mathrm{1};\mathrm{2},\mathrm{2},\mathrm{2};{x}\right) \\ $$$${we}\:{Get} \\ $$$$\int\frac{{e}^{{x}} {ln}\left({x}\right)}{{x}}{dx}={E}_{{i}} \left({x}\right){ln}\left({x}\right)−\gamma{ln}\left({x}\right)−\frac{{ln}^{\mathrm{2}} \left({x}\right)}{\mathrm{2}}−{x}\:_{\mathrm{3}} {F}_{\mathrm{3}} \left(\mathrm{1},\mathrm{1},\mathrm{1};\mathrm{2},\mathrm{2},\mathrm{2};{x}\right)+{c} \\ $$$$=\frac{{ln}\left({x}\right)}{\mathrm{2}}\left({Ei}\left({x}\right)−\mathrm{2}\gamma+{ln}\left(\frac{\mathrm{1}}{{x}}\right)\right)−{x}\:_{\mathrm{3}} {F}_{\mathrm{3}} \left(\mathrm{1},\mathrm{1},\mathrm{1};\mathrm{2},\mathrm{2},\mathrm{2};{x}\right)+{c} \\ $$$$ \\ $$ | ||