答：a=1,b=3
1/(ab)+1/[(a+2)(b+2)]+1/[(a+4)(b+4)]+1/[(a+6)(b+6)]+.+1/[(a+100)(b+100)]
=1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+.+1/(101×103)
=(1/2)[2/(1×3)+2/(3×5)+2/(5×7)+2/(7×9)+.+2/(101×103)]
=(1/2)(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+...+1/101-1/103)
=(1/2)(1-1/103)
=(1/2)(102/103)
=51/103为什么我算到102/103，是哪出问题了？为什么要乘以1/2？因为裂项后有1/2