计算(1−122)(1−132)…(1−192)(1−1102)=(  ) A.1021 B.1321 C.920 D.1120

问题描述:

计算(1−

1
22
)(1−
1
32
)…(1−
1
92
)(1−
1
102
)=(  )
A.
10
21

B.
13
21

C.
9
20

D.
11
20

原式=(1-

1
2
)(1+
1
2
)×(1-
1
3
)(1+
1
3
)×…×(1-
1
9
)×(1+
1
9
)×(1-
1
10
)×(1+
1
10
),
=
1
2
×
3
2
×
2
3
×
4
3
×…×
8
9
×
10
9
×
9
10
×
11
10

=
11
20

故选D.