Question Number 135385 by rs4089 last updated on 12/Mar/21
$$\mathrm{1}−\frac{\mathrm{1}}{\mathrm{2}}\:\frac{\mathrm{1}}{{x}^{\mathrm{2}} }+\frac{\mathrm{1}}{\mathrm{2}}\frac{\mathrm{3}}{\mathrm{4}}\:\frac{\mathrm{1}}{{x}^{\mathrm{4}} }−\frac{\mathrm{1}}{\mathrm{2}}\frac{\mathrm{3}}{\mathrm{4}}\frac{\mathrm{5}}{\mathrm{6}}\:\frac{\mathrm{1}}{{x}^{\mathrm{6}} }+….=? \\ $$