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1-prove-that-k-1-n-H-k-n-1-H-n-n-2-prove-that-k-1-n-H-k-2-n-1-H-n-2-3n-1-H-n-2n-H-n-k-1-n-1-k-

Question Number 34596 by abdo mathsup 649 cc last updated on 08/May/18 $$\left.\mathrm{1}\right)\:{prove}\:{that}\:\:\sum_{{k}=\mathrm{1}} ^{{n}} \:{H}_{{k}} =\left({n}+\mathrm{1}\right){H}_{{n}} \:−{n} \\ $$$$\left.\mathrm{2}\right)\:{prove}\:{that}\:\:\sum_{{k}=\mathrm{1}} ^{{n}} \:{H}_{{k}} ^{\mathrm{2}} \:\:=\left({n}+\mathrm{1}\right){H}_{{n}} ^{\mathrm{2}} \:\:−\left(\mathrm{3}{n}+\mathrm{1}\right){H}_{{n}}…

1-1-32-1-243-1-1024-

Question Number 100000 by Dwaipayan Shikari last updated on 24/Jun/20 $$\mathrm{1}+\frac{\mathrm{1}}{\mathrm{32}}+\frac{\mathrm{1}}{\mathrm{243}}+\frac{\mathrm{1}}{\mathrm{1024}}+…\infty \\ $$ Commented by ajfour last updated on 27/Jun/20 $${this}\:{question}\:{number}\:{is}\:{a}\: \\ $$$${landmark},\:{congratulations} \\ $$$${to}\:{all}\:{of}\:{us}\:\:{related}\:{with}\:{this}\:…

1-x-x-2-x-1-dx-

Question Number 165528 by LEKOUMA last updated on 03/Feb/22 $$\int\frac{\mathrm{1}}{{x}+\sqrt{{x}^{\mathrm{2}} +{x}+\mathrm{1}}}{dx} \\ $$ Commented by mkam last updated on 03/Feb/22 $$=\:\int\:\frac{\sqrt{{x}^{\mathrm{2}} +{x}+\mathrm{1}}\:−{x}}{\left({x}+\mathrm{1}\right)}\:{dx}\:=\:\int\:\frac{\sqrt{\left({x}+\frac{\mathrm{1}}{\mathrm{2}}\right)^{\mathrm{2}} +\frac{\mathrm{3}}{\mathrm{4}}}}{\left({x}+\mathrm{1}\right)}\:−\:\frac{\left({x}+\mathrm{1}−\mathrm{1}\right)}{\left({x}+\mathrm{1}\right)}\:{dx} \\ $$$$…