1/4+1/28+1/70+1/130+1/来自208怎样简便运算

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最佳答案

回答者:网友
裂项法:
1/4+1/28+1/70+1/130+1/208
=1/3×(1-1/4+1/4-1/7+1/7-1/10+1/10-1/13+1/13-1/16)
=1/3×(1-1/16)
=1/3×15/16
=5/16

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