五年级数学分数计算题1/15+1/35+1/63+1/99+1/143
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五年级数学分数计算题1/15+1/35+1/63+1/99+1/143
![五年级数学分数计算题1/15+1/35+1/63+1/99+1/143](/uploads/image/z/5560704-0-4.jpg?t=%E4%BA%94%E5%B9%B4%E7%BA%A7%E6%95%B0%E5%AD%A6%E5%88%86%E6%95%B0%E8%AE%A1%E7%AE%97%E9%A2%981%2F15%2B1%2F35%2B1%2F63%2B1%2F99%2B1%2F143)
1/15+1/35+1/63+1/99+1/143
=1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)+1/(11*13)
=1/2(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)
=1/2*(1/3-1/13)
=1/2*10/39
=5/39
=1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)+1/(11*13)
=1/2(1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13)
=1/2*(1/3-1/13)
=1/2*10/39
=5/39