Question

(1/2+1/3+.+1/2000+1/2001)-(1+1/2+1/3+..+1/2001)(1/2+1/3+...+

Answer 1

题目漏了,前面应该还有,我记得我做过不少遍!

假设t=1/2+1/3+...+1/2000,则

原式

=(1+t)(t+1/2001)-(1+t+1/2001)t

=t^2+t+t/2001+1/2001-t-t^2-t/2001

=1/2001