Recall that the {\sl interval of convergence} of a power series is the
set of numbers~$x$ for which the power series converges.  What is the
interval of convergence for the series $\sum \frac {x^n}{n}$ ?
\correct $[-1,1)$
\wrong $(-\infty,\infty)$
\wrong $(-1,1)$
\wrong $(0,\infty)$
\wrong $[-1,1]$
