1/1*3+1/3*5+1/5*7+……+1/97*99+1/99*101

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1/1*3+1/3*5+1/5*7+……+1/97*99+1/99*101

1/1*3+1/3*5+1/5*7+……+1/97*99+1/99*101
1/1*3+1/3*5+1/5*7+……+1/97*99+1/99*101

1/1*3+1/3*5+1/5*7+……+1/97*99+1/99*101
1/[n(n+2)]=1/2*[1/n-1/(n+2)]
原式=1/2*(1-1/3+1/3-1/5+……+1/99-1/101)
=1/2*(1-1/101)
=50/101

1/1*3+1/3*5+1/5*7+……+1/97*99+1/99*101
=(1/2)(2/1*3+2/3*5+2/5*7+……+2/97*99+2/99*101)
=(1/2)[(1/1-1/3)+(1/3-1/5)+……+(1/99-1/101)
=(1/2)(1/1-1/101)
=50/101

1/1*3+1/3*5+1/5*7+……+1/97*99+1/99*101=1/2(1/1-1/3+1/3-1/5+1/5-1/7+……+1/97-1/99+1/99-1/101)=1/2(1-1/101)=1/2*100/101=50/101

1/1*3+1/3*5+1/5*7+......+1/99*101
=(1/2)[(1-1/3)+(1/3-1/5)+(1/5-1/7)+......+(1/99-1/101)]
=(1/2)(1-1/3+1/3-1/5+1/5-1/7+......+1/99-1/101)
=(1/2)(1-1/101)
=(1/2)×(100/101)
=50/101