4·7×2·8+2·5×2·8+7·2×7·2﹙简便运算,用递等式计算﹚
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4·7×2·8+2·5×2·8+7·2×7·2﹙简便运算,用递等式计算﹚
4·7×2·8+2·5×2·8+7·2×7·2﹙简便运算,用递等式计算﹚
4·7×2·8+2·5×2·8+7·2×7·2﹙简便运算,用递等式计算﹚
4·7×2·8+2·5×2·8+7·2×7·2
=2.8×(4.7+2.5)+7·2×7·2
=2.8×7·2+7·2×7·2
=7.2x(2.8+7.2)
=7.2x10
=72
2.8×(4.7+2.5+7.2)
4·7×2·8+2·5×2·8+7·2×7·2﹙简便运算,用递等式计算﹚
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