裂项法数列求和的详细内容
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比如下列的裂项法::
(1)1/n(n+1)=1/n-1/(n+1)
(2)1/(2n-1)(2n+1)=1/2[1/(2n-1)-1/(2n+1)]
(3)1/n(n+1)(n+2)=1/2[1/n(n+1)-1/(n+1)(n+2)]
(4)1/(√a+√b)=[1/(a-b)](√a-√b)
(5)n·n!=(n+1)!-n!
(6)n/(n+1)!=1/n!-1/(n+1)!
(7)n^2=n(n+1)-n=[(n+2)(n+1)n-(n+1)n(n-1)]/3-n
(8)n^3=n(n+1)(n+2)-3n^2-2n=[(n+3)(n+2)(n+1)n-(n+2)(n+1)n(n-1)]/4-3n^2-2n
(1)1/n(n+1)=1/n-1/(n+1)
(2)1/(2n-1)(2n+1)=1/2[1/(2n-1)-1/(2n+1)]
(3)1/n(n+1)(n+2)=1/2[1/n(n+1)-1/(n+1)(n+2)]
(4)1/(√a+√b)=[1/(a-b)](√a-√b)
(5)n·n!=(n+1)!-n!
(6)n/(n+1)!=1/n!-1/(n+1)!
(7)n^2=n(n+1)-n=[(n+2)(n+1)n-(n+1)n(n-1)]/3-n
(8)n^3=n(n+1)(n+2)-3n^2-2n=[(n+3)(n+2)(n+1)n-(n+2)(n+1)n(n-1)]/4-3n^2-2n
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