題目 5. (10 Points) Find the radius of convergence of the power series ∑n=1∞n2xn\sum_{n=1}^{\infty} n^2x^n∑n=1∞n2xn and evaluate ∑n=1∞n22n\sum_{n=1}^{\infty}\dfrac{n^2}{2^n}∑n=1∞2nn2. 解答
