题目内容
用递等式计算.
(1)3-
-
;
(2)
×
+
×
;
(3)63×(
+
-
);
(4)(235-270÷18)×1.5.
(1)3-
7 |
12 |
5 |
12 |
(2)
5 |
7 |
3 |
8 |
5 |
8 |
5 |
7 |
(3)63×(
5 |
9 |
4 |
21 |
3 |
7 |
(4)(235-270÷18)×1.5.
考点:分数的四则混合运算
专题:运算顺序及法则
分析:(1)根据除法的性质简算;
(2)(3)运用乘法分配律简算;
(4)先算除法,再算法,最后算乘法.
(2)(3)运用乘法分配律简算;
(4)先算除法,再算法,最后算乘法.
解答:
解:(1)3-
-
=3-(
+
)
=3-1
=2;
(2)
×
+
×
=
×(
+
)
=
;
(3)63×(
+
-
)
=63×
+63×
-63×
=35+12-27
=20;
(4)(235-270÷18)×1.5
=(235-15)×1.5
=220×1.5
=330.
7 |
12 |
5 |
12 |
=3-(
7 |
12 |
5 |
12 |
=3-1
=2;
(2)
5 |
7 |
3 |
8 |
5 |
8 |
5 |
7 |
=
5 |
7 |
3 |
8 |
5 |
8 |
=
5 |
7 |
(3)63×(
5 |
9 |
4 |
21 |
3 |
7 |
=63×
5 |
9 |
4 |
21 |
3 |
7 |
=35+12-27
=20;
(4)(235-270÷18)×1.5
=(235-15)×1.5
=220×1.5
=330.
点评:此题考查的目的是理解掌握四则混合运算的顺序,以及它们的计算法则,并且能够灵活选择简便方法进行计算.
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