1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11(简算)

问题描述:

1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11(简算)

1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11
=1/2-1/3 + 1/3-1/4 + 1/4-1/5 + 1/5-1/6 + 1/6-1/7 + 1/7-1/8 + 1/8-1/9 + 1/9-1/10 + 1/10-1/11
=1/2-1/11
=9/22

=1/2-1/3+1/3-1/4+1/4-1/5+.......1/9-1/10+1/10-1/11
=1/2-1/11
=9/22

原式=1/2-1/3+1/3-1/4+1/5-1/6+……+1/10-1/11
=1/2-1/11
=9/22