(x-1)-(x-1)^2+(x-1)^3-(x-1)^4+(x-1)^5展开式中,求x^2的系数

问题描述:

(x-1)-(x-1)^2+(x-1)^3-(x-1)^4+(x-1)^5展开式中,求x^2的系数

(x-1)-(x-1)^2+(x-1)^3-(x-1)^4+(x-5)^5的展开式中x^2的系数
-1-3-6-1250=-1260

-1+C32(-1)-C42+C52(-1)³
=-1-3-6-10
=-20