题目内容
【题目】下面各题写出必要的计算过程,能简便计算的要简便计算.
×75 × ×21× ×× ×+×
×+× ×(﹣) (+)× ×25×39 45×
13× ×9× ×× ×21× ××
17×
( +)×32 ×+× ××16 +× 44﹣72×.
【答案】×75=20;
×=;
×21×=3;
××=;
×+×,
=(+)×,
=;
×+×,
=+,
=;
×(﹣),
=×﹣×,
=﹣,
=;
(+)×,
=×+×,
=+,
=;
×25×39,
=××39,
=;
45×=;
13×=;
×9×=1;
××=;
×21×=3;
××=;
17×=9;
( +)×32,
=×32+×32,
=24+20,
=44;
×+×,
=(+)×,
=;
××16=;
+×,
=+,
=;
44﹣72×,
=44﹣30,
=14.
【解析】
试题分析:根据分数乘法的计算法则:用分子相乘的积作分子,分母相乘的积作分母,能约分的要约分;及乘法结合律和乘法分配律进行解答即可.
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