2*1/7+7*1/12+12*1/17+17*1/22怎样用简便方法计算?
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![2*1/7+7*1/12+12*1/17+17*1/22怎样用简便方法计算?](/uploads/image/z/374151-39-1.jpg?t=2%2A1%2F7%2B7%2A1%2F12%2B12%2A1%2F17%2B17%2A1%2F22%E6%80%8E%E6%A0%B7%E7%94%A8%E7%AE%80%E4%BE%BF%E6%96%B9%E6%B3%95%E8%AE%A1%E7%AE%97%3F)
2*1/7+7*1/12+12*1/17+17*1/22怎样用简便方法计算?
2*1/7+7*1/12+12*1/17+17*1/22怎样用简便方法计算?
2*1/7+7*1/12+12*1/17+17*1/22怎样用简便方法计算?
2*1/7+7*1/12+12*1/17+17*1/22
=2/7+7/12+12/17+17/22
=(1-5/7)+(1-5/12)+(1-5/17)+(1-5/22)
=4-5(1/7+1/12+1/17+1/22)
=4-5[29/(7*22)+29/(12*17)]
=4-145(1/154+1/204)
=4-145[(102+77)/(77*2*102)]
=4-25955/15708
=2又5461/15708