Consider the power series \(\sum _{k=0}^{\infty } \frac {k!}{7^k (k+1)}(x-5)^k\).

The radius of convergence for the power series is \(\answer {0}\).

The lefthand endpoint of the “interval" of convergence is \(x=\answer {5}\) and the righthand endpoint is \(x= \answer {5}\).

This means that the power series:

does not convergence for any real \(x\)-values. converges only at the center \(x=5\); the domain of the function is a single point rather than an interval!