Question

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90用什么方

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90用什么方法，怎么做

Answer 1

裂项法

追答

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1-1/2-1/3+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+1/10
=1.1

有错，改:

1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1-1/2-1/3+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
=1/2+1/10
=3/5

Answer 2

Answer 3

追答

行家解答，质量保证

Answer 4

=1-1/2-1/3+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
=1/2+1/10
=3/5

5/6=1/2+1/3,7/12=1/3+1/4,以此类推。

Answer 5