- #1

- 8

- 1

$$

\sum_{{\rm n}=0}^\infty \left (-\sqrt x \right )^n \ \ \rm ?$$

Find the interval of convergence?

I tried using the root test and got from 0 to 1 but when I checked with Wolfram and it gave from -1 to 1 saying the absolute value would go inside the square root. Am I doing something wrong or is Wolfram making a mistake. Thanks in advance for any help.