1/1×2+1/2×3+1/3×4+1/4×5+1/5×6+1/6×7+1/7×8+1/8×9+1/9×10……1/49×50=?最好能有具体的简便计算过程

问题描述:

1/1×2+1/2×3+1/3×4+1/4×5+1/5×6+1/6×7+1/7×8+1/8×9+1/9×10……1/49×50=?
最好能有具体的简便计算过程

∵1/[n·﹙n+1﹚]=[﹙n+1﹚-n]/[n·﹙n+1﹚]=1/n-1/﹙n+1﹚
∴原式=(1-1/2)+(1/2-1/3)+....+(1/49-1/50)=1-1/50=49/50

原式=(1-1/2)+(1/2-1/3)+.+(1/49-1/50)=1-1/50=49/50.