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很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难

=很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难很难
1*2*3*4*.*n
n!=1*2*3*...*n
n1!=n*(n-1)*(n-2)*(n-3).3*2*1

n!=1*2*3*...*n

n！=1*2*3*4*5……*n

1*2*3*4*......*（n-1)*n

n1!=n*(n-1)*(n-2)*(n-3).......3*2*1
哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪...

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n1!=n*(n-1)*(n-2)*(n-3).......3*2*1
哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难哪里难

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n!=1脳2脳3脳钬γ枭

1*2*3*4*......*n

n!=1×2×3×……×n

表示n的阶乘
n!=1*2*3*...*n

5!=5*4*3*2*1=120 n!=n*(n-1)*(n-2)*(n-3).......3*2*1 就是一个数学 符号而已

就是从1依次乘到n啊。。。

n!=1×2×3×……×n
n的阶乘

n*(n-1)!(laigegexingde)

就是n的阶乘，1×2×3×4……×n

！表示阶乘，n！表示从1一直乘到n，
只是一个符号，为了写起来简单而已，就像∑一样

你是不是要斯特林公式呀 一下证明
令a(n)=n! / [ n^(n+1/2) * e^(-n) ]
则a(n) / a(n+1) = (n+1)^(n+3/2) / [ n^(n+1/2) * (n+1) * e ]
=(n+1)^(n+1/2) / [ n^(n+1/2) * e]
=(1+1/n)^n * (1+1/n)^1/2 *1/e
...

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你是不是要斯特林公式呀 一下证明
令a(n)=n! / [ n^(n+1/2) * e^(-n) ]
则a(n) / a(n+1) = (n+1)^(n+3/2) / [ n^(n+1/2) * (n+1) * e ]
=(n+1)^(n+1/2) / [ n^(n+1/2) * e]
=(1+1/n)^n * (1+1/n)^1/2 *1/e
当n→∞时,(1+1/n)^n→e,(1+1/n)^1/2→1
即lim(n→∞) a(n)/a(n+1)=1
所以lim(n→∞)a(n) 存在
设A=lim(n→∞)a(n)
A=lim(n→∞)n! / [ n^(n+1/2) * e^(-n) ]
利用Wallis公式,π/2 = lim(n→∞)[ (2n)!! / (2n-1)!! ]^2 / (2n+1)
π/2 = lim(n→∞)[ (2n)!! / (2n-1)!! ]^2 / (2n+1)
=lim(n→∞)[ (2n)!! * (2n)!! / (2n)! ]^2 / (2n+1)
=lim(n→∞) 2^(4n) [ (n!)^2 / (2n)! ]^2 / (2n+1)
=lim(n→∞) 2^(4n) [ (A * n^(n+1/2) * e^(-n) )^2 / (A * (2n)^(2n+1/2) * e^(-2n) )]^2 / (2n+1)
=lim(n→∞) 2^(4n) [ 2^(-2n-1/2) * A * √n ]^2 / (2n+1)
=lim(n→∞) 2^(4n) * A^2 * 2^(-4n-1) * n/(2n+1)
=A^2 / 4
所以A=√(2π)
lim(n→∞)n! / [ n^(n+1/2) * e^(-n) ] = √(2π)
即lim(n→∞) √(2πn) * n^n * e^(-n) / n! = 1
这是最早 也是最公认的证法

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n!=1*2*3*...*n

就是n的阶乘啊，从1一直连乘到n既
n!=1*2*3*...*n

n!=3.141592653.............

！表示阶乘，n！即n的阶乘，
表示从1一直乘到n：
n!=1×2×3×……×n

1*2*3*4*......*n