7/12x1/5+5/12x7/5 (1/5+1/ - 知识问答

7/12x1/5+5/12x7/5 (1/5+1/7)x5x7 （用简便方法计算）今晚作业明天交不了,明天要挨批了

1个回答

7/12x1/5+5/12x7/5
=7/12×1/5+7/12×5/5
=7/12×(1/5+1)
=7/12×6/5
=7/10
(1/5+1/7)x5x7
=5×7×1/5+5×7×1/7
=7+5
=12

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