求值;ab/1+【a+1】乘【b+1】/1+【a+2】乘【b+2】+.+【a+2014】乘【b+2014]/1

问题描述:

求值;ab/1+【a+1】乘【b+1】/1+【a+2】乘【b+2】+.+【a+2014】乘【b+2014]/1
已知ab减二的绝对值与1减a的绝对值互为相反数,

答:
|ab-2|和|1-a|互为相反数,相反数之和为0:
|ab-2|+|1-a|=0
绝对值为非负数,则:ab-2=0
1-a=0
解得:a=1,b=2
1/(ab)+1/[(a+1)(b+1)]+1/[(a+2)(b+2)]+.+1/[(a+2014)(b+2014)]
=1/(1×2)+1/(2×3)+1/(3×4)+.+1/(2015×2016)
=1-1/2+1/2-1/3+1/3-1/4+.+1/2015-1/2016 (中间各项正负相抵消)
=1-1/2016
=2015/2016