16) Find the series' radius of convergence.

n=0 (x-2)²ⁿ/4ⁿ

17) Find the interval of convergence of the series.

n=0 (x - 9)ⁿ/9n + 7

18) Find the first four terms of the binomial series for the given function.

(1 + 9x)^1/2

19) Use series to evaluate the limit.

lim x->0 e^2x -1/x

20) Find the sum of the series as a function of x

n=0 (x-3/6)ⁿ