f(n)=1/n+1+1/n+2+/1n+3+......+1/2n(n包涵正整数那么f(n+1)-f(n)=
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f(n)=1/(n+1)+1/(n+2)+1/(n+3)+......+1/2n
f(n+1)=1/(n+2)+1/(n+3)+....+1/(2n+1)+1/(2n+2)
f(n+1)-f(n)=[1/(n+2)+1/(n+3)+....+1/(2n+1)]-[1/(n+1)+1/(n+2)+1/(n+3)+......+1/2n]
=1/(2n+1)+1/(2n+2)-1/(n+1)
=1/(2n+1)-1/(2n+2)
=1/(2n+1)(2n+2)
f(n+1)=1/(n+2)+1/(n+3)+....+1/(2n+1)+1/(2n+2)
f(n+1)-f(n)=[1/(n+2)+1/(n+3)+....+1/(2n+1)]-[1/(n+1)+1/(n+2)+1/(n+3)+......+1/2n]
=1/(2n+1)+1/(2n+2)-1/(n+1)
=1/(2n+1)-1/(2n+2)
=1/(2n+1)(2n+2)
来自:求助得到的回答
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把n+1代入f(n),发现首项变成1/(n+2),少了1/(n+1),后边多了1/(2n+1)+1/(2n+2)
相减后得到 1/(2n+1)+1/(2n+2)-1/(n+1)
整理后得:1/(2n+1)-1/(2n+2) = 1/2(n+1)(2n+1)
相减后得到 1/(2n+1)+1/(2n+2)-1/(n+1)
整理后得:1/(2n+1)-1/(2n+2) = 1/2(n+1)(2n+1)
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f(n+1)=1/(n+2)+1/(n+2)+……+1/2n+1/(2n+1)+1/(2n+2)
f(n+1)-f(n)=1/(2n+1)+1/(2n+2)-1/(n +1)=1/(2n+1)-1/(2n+2)=1/(2n+1)(2n+2)
f(n+1)-f(n)=1/(2n+1)+1/(2n+2)-1/(n +1)=1/(2n+1)-1/(2n+2)=1/(2n+1)(2n+2)
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