(1+12)×(1-12)×(1+13)×(1-13)×…×(1+199)×(1-199)等于______.-数学

题目简介

(1+12)×(1-12)×(1+13)×(1-13)×…×(1+199)×(1-199)等于______.-数学

题目详情

(1+
1
2
)×(1-
1
2
)×(1+
1
3
)×(1-
1
3
)×…×(1+
1
99
)×(1-
1
99
)
等于______.
题型:解答题难度:中档来源:不详

答案

(1+class="stub"1
2
)×(1-class="stub"1
2
)×(1+class="stub"1
3
)×(1-class="stub"1
3
)×…×(1+class="stub"1
99
)×(1-class="stub"1
99
)

=[(1+class="stub"1
2
)×(1+class="stub"1
3
)×…×(1+class="stub"1
99
)]×[(1-class="stub"1
2
)×(1-class="stub"1
3
)×…×(1-class="stub"1
99
)],
=[class="stub"3
2
×class="stub"4
3
×…×class="stub"100
99
]×[class="stub"1
2
×class="stub"2
3
×…×class="stub"98
99
],
=class="stub"100
2
×class="stub"1
99

=class="stub"50
99

故答案为:class="stub"50
99

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