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2又3/4+{5又1/4-0.04-(1又5/8-2又1/5)-0.1+1/2}培优题,
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2又3/4+{5又1/4-【0.04-(1又5/8-2又1/5)-0.1】+1/2} 培优题,
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答案和解析
2又3/4=2+3/4就都这样写了,好做,也清楚,真的计算也应该如此
原式=2+3/4+{5+1/4-[0.04-(1+5/8-(2+1/5))-0.1]+1/2}
简单方法就是发现都是可以化为有限小数的分数
=2+0.75+{5+0.25-[0.04-(1+0.625-(2+0.2))-0.1]+0.5}
=2+0.75+{5+0.25-[0.04-(1.625-2.2)-0.1]+0.5}
=2.75+{5.25-[0.04-(-0.575)-0.1]+0.5}
=2.75+{5.25-[0.04+0.575-0.1]+0.5}
=2.75+{5.25-0.515+0.5}
=2.75+5.235
=7.985
原式=2+3/4+{5+1/4-[0.04-(1+5/8-(2+1/5))-0.1]+1/2}
简单方法就是发现都是可以化为有限小数的分数
=2+0.75+{5+0.25-[0.04-(1+0.625-(2+0.2))-0.1]+0.5}
=2+0.75+{5+0.25-[0.04-(1.625-2.2)-0.1]+0.5}
=2.75+{5.25-[0.04-(-0.575)-0.1]+0.5}
=2.75+{5.25-[0.04+0.575-0.1]+0.5}
=2.75+{5.25-0.515+0.5}
=2.75+5.235
=7.985
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