
观察下列各式,1/1*2=1-1/2 1/2*3=1/2-1/3,1/3*4=1/3-1/4
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1/2*4+1/4*6+...+1/2n*2(n+1)
=1/4(1/1*2)+1/4(1/2*3)+...+1/4*(1/n(n+1))
=1/4(1/1-1/2+1/2-1/3+...+1/n-1/(n+1))
=1/4(1-1/(n+1))
=1/4*n/(n+1)
=n/(4n+4) 或n/[4(n+1)]
有疑问,请追问;若满意,请采纳,谢谢!
=1/4(1/1*2)+1/4(1/2*3)+...+1/4*(1/n(n+1))
=1/4(1/1-1/2+1/2-1/3+...+1/n-1/(n+1))
=1/4(1-1/(n+1))
=1/4*n/(n+1)
=n/(4n+4) 或n/[4(n+1)]
有疑问,请追问;若满意,请采纳,谢谢!
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