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求证:C0nC1n+C1nC2n+…+Cn-1nCnn=(2n)!(n-1)!(n+1)!.
题目详情
求证:C
+
+…+
=
.
0 n |
C | 1 n |
|
C | 2 n |
C | n-1 n |
C | n n |
(2n)! |
(n-1)!(n+1)! |
▼优质解答
答案和解析
证明:∵(x+1)n(x+1)n=(x+1)2n,
则左边xn-1的系数为:C
+
+…+
,右边xn-1的系数=
=
.
∴C
+
+…+
=
.
则左边xn-1的系数为:C
0 n |
C | 1 n |
|
C | 2 n |
C | n-1 n |
C | n n |
∁ | n-1 2n |
(2n)! |
(n-1)!(n+1)! |
∴C
0 n |
C | 1 n |
|
C | 2 n |
C | n-1 n |
C | n n |
(2n)! |
(n-1)!(n+1)! |
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