求(1+1/2+1/3+..+1/2013)(1/2+1/3+1/2004)-(1+1/2+1/3+...+1/2004)(1/2_数学解答

求(1+1/2+1/3+..+1/2013)(1/2+1/3+1/2004)-(1+1/2+1/3+...+1/2004)(1/2+1/3+...+1/2003)的值

人气：496 ℃　时间：2020-10-01 20:48:39

解答

设x=1/2+1/3+..+1/2013
y=1/2+1/3+……+1/2004
(1+1/2+1/3+..+1/2013)(1/2+1/3+……+1/2004)-(1+1/2+1/3+...+1/2004)(1/2+1/3+...+1/2003)
=(1+x)y-(1+y)x
=y+xy-x-xy
=y-x
=1/2004