Chapter 9, Problem 34RE

In each part, write out the first four terms of the series, and then find the radius of convergence.

$\begin{array}{l}\text{(a)}{\displaystyle \underset{k=1}{\overset{\infty }{\sum }}\frac{\mathrm{1.2.3...}k}{\mathrm{1.4.7...}(3k-2)}{x}^k}\\ \text{(b)}{\displaystyle \underset{k=1}{\overset{\infty }{\sum }}{(-1)}^k\frac{\mathrm{1.2.3...}k}{\mathrm{1.3.5...}(2k-1)}{x}^{2k+1}}\end{array}$