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8.7×1.9-8.7×0.9 2.5×3.8×0.4×0.2 5.7×10.2.
分析:(1)(3)根据乘法分配律简便计算;
(2)根据乘法交换律和结合律简便计算.
解答:解:(1)8.7×1.9-8.7×0.9
=8.7×(1.9-0.9)
=8.7×1
=8.7;

(2)2.5×3.8×0.4×0.2
=(2.5×0.4)×(3.8×0.2)
=1×0.76
=0.76;

(3)5.7×10.2
=5.7×(10+0.2)
=5.7×10+5.7×0.2
=57+1.14
=58.14.
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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