1-1/6+1/42+1/56+1/72+1/90

1-1/6+1/42+1/56+1/72+1/90+1/110怎么简便

1个回答

1-1/6+1/42+1/56+1/72+1/90+1/110
=1-1/6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11
=1-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11
=1-1/11
=10/11