将f(x)展开成x的幂级数 求步骤

如题所述

第1个回答  推荐于2016-05-08
利用
1/(1-x) = ∑(n≥0)(x^n),|x|<1,
可得
f(x) = x/[(x-2)(x+1)]
= (1/3)/(x+1) + (2/3)/(x-2)
= (1/3)/(1+x) - (1/3)/(1-x/2)
= (1/3) ∑(n≥0)[(-x)^n] - (1/3)∑(n≥0)[(x/2)^n]
= ……,|x|<1。本回答被提问者采纳