计算题:1/3+1/15+1/35+1/63+1/99+1/143

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计算题:1/3+1/15+1/35+1/63+1/99+1/143
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计算题:1/3+1/15+1/35+1/63+1/99+1/143
计算题:1/3+1/15+1/35+1/63+1/99+1/143

计算题:1/3+1/15+1/35+1/63+1/99+1/143
1/3+1/15+1/35+1/63+1/99+1/143
=1/2*[2*(1/3+1/15+1/35+1/63+1/99+1/143)]
=1/2*[2/3+2/15+2/35+2/63+2/99+2/143]
=1/2*[(1-1/3)+(1/3-1/5)+(1/5-1/7)+(1/7-1/9)+(1/9-1/11)+(1/11-1/13)]
=1/2*(1-1/13)
=6/13

1/3+1/15+1/35+1/63+1/99+1/143
=1/(1*3)+1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)+1/(11*13)
=1/2*(1-1/3+1/3+1/5+...........+1/11-1/13)
=1/2*(1-1/13)
=6/13


1/3+1/15+1/35+163+1/99+1/143
=1/2(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)
=1/2*12/13
=6/13

6/13

有这样一个规律:1/(1×3) = 1/2 ×(1-1/3)
1/(3×5) = 1/2×(1/3-1/5)
如此类推
下面就用这个规律解题:
1/3+1/15+1/35+1/63+1/99+1/143
= 1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+1/(9×11)+1/(11×13)
=1/2...

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有这样一个规律:1/(1×3) = 1/2 ×(1-1/3)
1/(3×5) = 1/2×(1/3-1/5)
如此类推
下面就用这个规律解题:
1/3+1/15+1/35+1/63+1/99+1/143
= 1/(1×3)+1/(3×5)+1/(5×7)+1/(7×9)+1/(9×11)+1/(11×13)
=1/2(1-1/3)+1/2(1/3-1/5)+1/2(1/5-1/7)+……+1/2(1/11-1/13)
= 1/2(1-1/3+1/3-1/5+1/5-1/7+……+1/11-1/13)
= 1/2(1-1/13)
= 6/13

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