问题 解答题
(1+
1
2
)×(1-
1
2
)×(1+
1
3
)×(1-
1
3
)×…×(1+
1
10
)×(1-
1
10
答案

(1+

1
2
)×(1-
1
2
)×(1+
1
3
)×(1-
1
3
)×…×(1+
1
10
)×(1-
1
10

=(1-

1
2
)×(1+
1
2
)×(1-
1
3
)×(1+
1
3
)×…×(1-
1
10
)×(1+
1
10
),

=

1
2
×(
3
2
×
2
3
×
4
3
×
3
4
×…×
9
10
)×
11
10

=

1
2
×1×
11
10

=

11
20

单项选择题
单项选择题