计算1/x(x+2)+1/(x+2)(x+4)+…+1/(x+98)(x+100)

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计算1/x(x+2)+1/(x+2)(x+4)+…+1/(x+98)(x+100)

计算1/x(x+2)+1/(x+2)(x+4)+…+1/(x+98)(x+100)
计算1/x(x+2)+1/(x+2)(x+4)+…+1/(x+98)(x+100)

计算1/x(x+2)+1/(x+2)(x+4)+…+1/(x+98)(x+100)
1/x(x+2)+1/(x+2)*(x++4)+1/(x+4)*(x+6)+.+1/(x+98)*(x+100)
=[2/x(x+2)+2/(x+2)*(x++4)+2/(x+4)*(x+6)+.+2/(x+98)*(x+100)]/2
=[1/x-1/(x+2)+1/(x+2)-1/(x+4)+……+1/(x+98)-1/(x+100)]/2
=[1/x-1/(x+100)]/2
=(x+100-x)/2x(x+100)
=50/x(x+100)
=50/2*102
=25/102

1/x(x+2)+1/(x+2)(x+4)+…+1/(x+98)(x+100)=1/2(1/x-1/(x+2)+1/(x+2)……-1/(x+100))=50/x(x+100)

此法叫裂项