试解方程：2/(x+1)(x+2) + 2/(x+2)(x+3)＋ … ＋2/(x+10)(x+11)=5x/(x+1)(x+11)

分类: 作业答案 • 2022-03-11 16:09:30

问题描述：

答

裂项求和
即 2(1/(x+1)-1/(x+2))+2(1/(x+2)-1/(x+3))+...2(1/(x+10)-1/(x+11))
=5x/(x+1)(x+11)
即 2*10=5x
所以 x=4