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4-3-9-8-49-48-121-120-169-168-289-288-529-528-831-830-




Question Number 117258 by Dwaipayan Shikari last updated on 10/Oct/20
(4/3).(9/8).((49)/(48)).((121)/(120)).((169)/(168)).((289)/(288)).((529)/(528)).((831)/(830)).....∞
$$\frac{\mathrm{4}}{\mathrm{3}}.\frac{\mathrm{9}}{\mathrm{8}}.\frac{\mathrm{49}}{\mathrm{48}}.\frac{\mathrm{121}}{\mathrm{120}}.\frac{\mathrm{169}}{\mathrm{168}}.\frac{\mathrm{289}}{\mathrm{288}}.\frac{\mathrm{529}}{\mathrm{528}}.\frac{\mathrm{831}}{\mathrm{830}}…..\infty \\ $$
Answered by AbduraufKodiriy last updated on 10/Oct/20
βˆ’ { ((𝛇(2)=(1/1^2 )+(1/2^2 )+(1/3^2 )+...)),(((1/2^2 )𝛇(2)=(1/2^2 )+(1/4^2 )+(1/6^2 )+...)) :}β‡’ (1βˆ’(1/2^2 ))𝛇(2)=(1/1^2 )+(1/3^2 )+(1/5^2 )+(1/7^2 )+(1/9^2 )+... β‡’  β‡’ βˆ’ { (((1βˆ’(1/2^2 ))𝛇(2)=(1/1^2 )+(1/3^2 )+(1/5^2 )+...)),(((1/3^2 )(1βˆ’(1/2^2 ))𝛇(2)=(1/3^2 )+(1/9^2 )+(1/(15^2 ))+...)) :}β‡’  β‡’ (1βˆ’(1/3^2 ))(1βˆ’(1/2^2 ))𝛇(2)=(1/1^2 )+(1/5^2 )+(1/7^2 )+(1/(11^2 ))+(1/(13^2 ))+...  ..............................  𝛇(2)(1βˆ’(1/2^2 ))(1βˆ’(1/3^2 ))(1βˆ’(1/5^2 ))...=1  (Ο€^2 /6)=(2^2 /(2^2 βˆ’1))βˆ™(3^2 /(3^2 βˆ’1))βˆ™(5^2 /(5^2 βˆ’1))βˆ™(7^2 /(7^2 βˆ’1))βˆ™...  (Ο€^2 /6)=(4/3)βˆ™(9/8)βˆ™((25)/(24))βˆ™((49)/(48))βˆ™... β‡’ ((4Ο€^2 )/(25))=(4/3)βˆ™(9/8)βˆ™((49)/(48))βˆ™((121)/(120))βˆ™...
$$βˆ’\begin{cases}{\boldsymbol{\zeta}\left(\mathrm{2}\right)=\frac{\mathrm{1}}{\mathrm{1}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{2}} }+…}\\{\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }\boldsymbol{\zeta}\left(\mathrm{2}\right)=\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{4}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{6}^{\mathrm{2}} }+…}\end{cases}\Rightarrow\:\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }\right)\boldsymbol{\zeta}\left(\mathrm{2}\right)=\frac{\mathrm{1}}{\mathrm{1}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{5}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{7}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{9}^{\mathrm{2}} }+…\:\Rightarrow \\ $$$$\Rightarrow\:βˆ’\begin{cases}{\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }\right)\boldsymbol{\zeta}\left(\mathrm{2}\right)=\frac{\mathrm{1}}{\mathrm{1}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{5}^{\mathrm{2}} }+…}\\{\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{2}} }\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }\right)\boldsymbol{\zeta}\left(\mathrm{2}\right)=\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{9}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{15}^{\mathrm{2}} }+…}\end{cases}\Rightarrow \\ $$$$\Rightarrow\:\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{2}} }\right)\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }\right)\boldsymbol{\zeta}\left(\mathrm{2}\right)=\frac{\mathrm{1}}{\mathrm{1}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{5}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{7}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{11}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{13}^{\mathrm{2}} }+… \\ $$$$………………………… \\ $$$$\boldsymbol{\zeta}\left(\mathrm{2}\right)\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{2}} }\right)\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{2}} }\right)\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{\mathrm{5}^{\mathrm{2}} }\right)…=\mathrm{1} \\ $$$$\frac{\pi^{\mathrm{2}} }{\mathrm{6}}=\frac{\mathrm{2}^{\mathrm{2}} }{\mathrm{2}^{\mathrm{2}} βˆ’\mathrm{1}}\centerdot\frac{\mathrm{3}^{\mathrm{2}} }{\mathrm{3}^{\mathrm{2}} βˆ’\mathrm{1}}\centerdot\frac{\mathrm{5}^{\mathrm{2}} }{\mathrm{5}^{\mathrm{2}} βˆ’\mathrm{1}}\centerdot\frac{\mathrm{7}^{\mathrm{2}} }{\mathrm{7}^{\mathrm{2}} βˆ’\mathrm{1}}\centerdot… \\ $$$$\frac{\pi^{\mathrm{2}} }{\mathrm{6}}=\frac{\mathrm{4}}{\mathrm{3}}\centerdot\frac{\mathrm{9}}{\mathrm{8}}\centerdot\frac{\mathrm{25}}{\mathrm{24}}\centerdot\frac{\mathrm{49}}{\mathrm{48}}\centerdot…\:\Rightarrow\:\frac{\mathrm{4}\pi^{\mathrm{2}} }{\mathrm{25}}=\frac{\mathrm{4}}{\mathrm{3}}\centerdot\frac{\mathrm{9}}{\mathrm{8}}\centerdot\frac{\mathrm{49}}{\mathrm{48}}\centerdot\frac{\mathrm{121}}{\mathrm{120}}\centerdot… \\ $$
Commented by Dwaipayan Shikari last updated on 10/Oct/20
Great sir!  So generally  ΞΆ(s)=Ξ _p ^∞ (1βˆ’(1/p^s ))^(βˆ’1) (p=prime Numbers)
$${Great}\:{sir}! \\ $$$${So}\:{generally} \\ $$$$\zeta\left({s}\right)=\underset{{p}} {\overset{\infty} {\prod}}\left(\mathrm{1}βˆ’\frac{\mathrm{1}}{{p}^{{s}} }\right)^{βˆ’\mathrm{1}} \left({p}={prime}\:{Numbers}\right) \\ $$

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