求幂级数∑(1,+∞)(n-1)x^n的和函数

2025-05-12 03:23:13
推荐回答(1个)
回答1:

S(x)/x²=(∑x^(n-1))'=(1/(1-x))'=1/(x-1)²
S(x)=x²/(x-1)²