\input epsf
\nopagenumbers
\magnification=\magstep1

\noindent {\bf Problem statement} In the following series $x$ is a
real number. In each case use the ratio test to determine the radius
of convergence of the series. Analyze the behavior of the series at
the endpoints in order to determine the interval of convergence.

\medskip

\settabs 3 \columns
\+a)  $\displaystyle\sum_{n=0}^{\infty}{ { {n}{x^n} } \over { n^2+1 } }$
&b) $\displaystyle\sum_{n=1}^{\infty} { {{n^2}{(x-1)^n} } \over { 2^n } }$
&c) $\displaystyle\sum_{n=1}^{\infty} { {{3^n} {x^n}}  \over  {n^2}  }$ \cr

\vfil\eject\end