题目内容
用脱式计算下面各题(能简算的要简算).
(
|
| ||||||||||||||
2-
|
|
分析:①利用乘法的分配律计算简便;
②把
看成0.75,利用乘法的分配律计算简便;
③先算
÷
,再利用一个数连续减去两个数,等于这个数减去这两个数的和计算简便;
④根据四则运算的顺序先算小括号里,再算中括号里,最后算括号外面的.
②把
3 |
4 |
③先算
6 |
13 |
9 |
26 |
④根据四则运算的顺序先算小括号里,再算中括号里,最后算括号外面的.
解答:解:①(
+
)×24,
=
×24+
×24,
=2+3,
=5;
②
×99+0.75,
=0.75×99+0.75,
=0.75×(99+1),
=0.75×100,
=75;
③2-
÷
-
,
=2-1
-
,
=2-(1
+
),
=2-2,
=0;
④
÷[
+(
-
)],
=
÷[
+
],
=
÷
,
=1.5.
1 |
12 |
1 |
8 |
=
1 |
12 |
1 |
8 |
=2+3,
=5;
②
3 |
4 |
=0.75×99+0.75,
=0.75×(99+1),
=0.75×100,
=75;
③2-
6 |
13 |
9 |
26 |
2 |
3 |
=2-1
1 |
3 |
2 |
3 |
=2-(1
1 |
3 |
2 |
3 |
=2-2,
=0;
④
5 |
8 |
1 |
3 |
5 |
6 |
3 |
4 |
=
5 |
8 |
1 |
3 |
1 |
12 |
=
5 |
8 |
5 |
12 |
=1.5.
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.
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