Question Number 133653 by greg_ed last updated on 23/Feb/21
![hi, everybody ! how to prove that 𝛑 is an irrational number ???](https://www.tinkutara.com/question/Q133653.png)
$$\boldsymbol{\mathrm{hi}},\:\boldsymbol{\mathrm{everybody}}\:! \\ $$$$\boldsymbol{\mathrm{how}}\:\boldsymbol{\mathrm{to}}\:\boldsymbol{\mathrm{prove}}\:\boldsymbol{\mathrm{that}}\:\boldsymbol{\pi}\:\boldsymbol{\mathrm{is}}\:\boldsymbol{\mathrm{an}}\:\boldsymbol{\mathrm{irrational}}\:\boldsymbol{\mathrm{number}}\:??? \\ $$
Answered by Dwaipayan Shikari last updated on 23/Feb/21
![1−(1/3)+(1/5)−(1/7)+(1/9)−(1/(11))+...=(π/4) As It is an Infinte series so it can never be rational Other series 1+(1/2^4 )+(1/3^4 )+...=(π^4 /(90)) 1+(1/2)((1/(2.1!)))^2 +(1/3)(((1.3)/(2^2 .2!)))^2 +(1/4)(((1.3.5)/(2^3 .3!)))^2 +...=(4/π)](https://www.tinkutara.com/question/Q133655.png)
$$\mathrm{1}−\frac{\mathrm{1}}{\mathrm{3}}+\frac{\mathrm{1}}{\mathrm{5}}−\frac{\mathrm{1}}{\mathrm{7}}+\frac{\mathrm{1}}{\mathrm{9}}−\frac{\mathrm{1}}{\mathrm{11}}+…=\frac{\pi}{\mathrm{4}} \\ $$$${As}\:{It}\:{is}\:{an}\:{Infinte}\:{series}\:{so}\:{it}\:{can}\:{never}\:{be}\:{rational} \\ $$$${Other}\:{series} \\ $$$$\mathrm{1}+\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{4}} }+\frac{\mathrm{1}}{\mathrm{3}^{\mathrm{4}} }+…=\frac{\pi^{\mathrm{4}} }{\mathrm{90}} \\ $$$$\mathrm{1}+\frac{\mathrm{1}}{\mathrm{2}}\left(\frac{\mathrm{1}}{\mathrm{2}.\mathrm{1}!}\right)^{\mathrm{2}} +\frac{\mathrm{1}}{\mathrm{3}}\left(\frac{\mathrm{1}.\mathrm{3}}{\mathrm{2}^{\mathrm{2}} .\mathrm{2}!}\right)^{\mathrm{2}} +\frac{\mathrm{1}}{\mathrm{4}}\left(\frac{\mathrm{1}.\mathrm{3}.\mathrm{5}}{\mathrm{2}^{\mathrm{3}} .\mathrm{3}!}\right)^{\mathrm{2}} +…=\frac{\mathrm{4}}{\pi} \\ $$