1/x(x+3) + 1/(x+3)(x+6)+...+1/(x+33)(x+36)=3/40

分类: 作业答案 • 2022-06-25 13:50:29

问题描述：

答

1/3*[1/x-1/(x+3)+1/(x+3)-1/(x+6)+……+1/(x+33)-1/(x+36)]=3/40
1/x-1/(x+36)=9/40
36/x(x+36)=9/40
x^2+36x=160
(x-4)(x+40)=0
x=4,x=-40