用递等式计算,能简便的要简便计算 8.3-2.4×1.523.4÷7.8+2.12.5×6.3+2.5×3.71.25×2.3×0.8.
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解:(1)8.3-2.4×1.5,
=8.3-3.6,
=4.7;
(2)23.4÷7.8+2.1,
=3+2.1,
=5.1;
(3)2.5×6.3+2.5×3.7,
=2.5×(6.3+3.7),
=2.5×10,
=25;
(4)1.25×2.3×0.8,
=1.25×0.8×2.3,
=1×2.3,
=2.3.
解析分析:(1)(2)按照先算第二级运算,再算第一级运算的顺序解答,(3)运用乘法分配律解答,(4)运用乘法交换律解答.
点评:本题考查知识点:(1)按照四则运算计算顺序正确进行计算,(2)正确运用简便算法解决问题.