1/2x3+1/3x4+1/4x5.+1/8x9+1/9x10
问题描述:
1/2x3+1/3x4+1/4x5.+1/8x9+1/9x10
答
1/2x3+1/3x4+1/4x5.+1/8x9+1/9x10
=(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+.+(1/8-1/9)+(1/9-1/10)
=1/2-1/10
=2/5