Question Number 119177 by help last updated on 22/Oct/20
Answered by Dwaipayan Shikari last updated on 22/Oct/20
$$\underset{{k}=\mathrm{0}} {\overset{\infty} {\sum}}\left(\frac{\mathrm{4}}{\mathrm{3}}\right)^{−{k}} =\mathrm{1}+\frac{\mathrm{3}}{\mathrm{4}}+\frac{\mathrm{3}^{\mathrm{2}} }{\mathrm{4}^{\mathrm{2}} }+…=\frac{\mathrm{1}}{\mathrm{1}−\frac{\mathrm{3}}{\mathrm{4}}}=\mathrm{4} \\ $$