求冪級(jí)數(shù)n(n+1)xn的收斂域及和函數(shù),并求常數(shù)項(xiàng)級(jí)數(shù)的和.
求級(jí)數(shù)的收斂域:.
求下列級(jí)數(shù)的收斂域:ne-nx.