Question Number 165834 by SANOGO last updated on 09/Feb/22
![l′expression de f(x) Σ_(n=o) ^(+oo) (((−1)^n )/(2n+1))x^n xε]o,1[](Q165834.png)
$${l}'{expression}\:{de}\:{f}\left({x}\right) \\ $$$$\left.\underset{{n}={o}} {\overset{+{oo}} {\sum}}\frac{\left(−\mathrm{1}\right)^{{n}} }{\mathrm{2}{n}+\mathrm{1}}{x}^{{n}} \:\:\:\:{x}\epsilon\right]{o},\mathrm{1}\left[\right. \\ $$