# Math Help - Student the power serie

1. ## Student the power serie

1)Student the power serie :

$\sum n^{(-1)^{n}}\times x^{n}$

in : $x = 1,x = \frac{1}{2}
$

2) Same question but :

$\left\{ \begin{array}{l}
x = a \\
\left| a \right| < 1 \\
\end{array} \right.
$

Give the radius and int of convergence

2. Since the $\lim _{n\rightarrow \infty }\limits n^{(-1)^n}\times x^n\neq 0$, we cannot conclude that the series converges.