题目内容
计算下面各题,能简便的一定要简便. 2-(
|
| ||||||||||||||
|
(
| ||||||||||||||
24×(
|
[
|
分析:(1)先算括号内的,再算括号外的乘法,最后算括号外的减法;
(2)把除法改为乘法,运用乘法分配律简算;
(3)把72
化为小数,把除法改为乘法,运用乘法分配律简算;
(4)运用乘法分配律和加法结合律简算;
(5)运用乘法分配律简算;
(6)中括号内运用减法的性质以及加法交换律与结合律简算.
(2)把除法改为乘法,运用乘法分配律简算;
(3)把72
4 |
5 |
(4)运用乘法分配律和加法结合律简算;
(5)运用乘法分配律简算;
(6)中括号内运用减法的性质以及加法交换律与结合律简算.
解答:解:(1)2-(
+
)×
,
=2-
×
,
=2-
,
=1
;
(2)
÷
-
÷
,
=
×
-
×
,
=(
-
)×
,
=1×
,
=
;
(3)
×72.8+72
÷4,
=
×72.8+72.8×
,
=72.8×(
+
),
=72.8×1,
=72.8;
(4)(
+
)×16+
,
=
×16+
×16+
,
=6+
+
,
=6+(
+
),
=6+1,
=7;
(5)24×(
+
-
),
=24×
+24×
-24×
,
=6+4-8,
=2;
(6)[
-(
-
)]×
,
=[(
-
+
)]×
,
=[
+
-
]×
,
=
×
,
=
.
1 |
4 |
1 |
7 |
4 |
11 |
=2-
11 |
28 |
4 |
11 |
=2-
1 |
7 |
=1
6 |
7 |
(2)
14 |
9 |
2 |
3 |
5 |
9 |
2 |
3 |
=
14 |
9 |
3 |
2 |
5 |
9 |
3 |
2 |
=(
14 |
9 |
5 |
9 |
3 |
2 |
=1×
3 |
2 |
=
3 |
2 |
(3)
3 |
4 |
4 |
5 |
=
3 |
4 |
1 |
4 |
=72.8×(
3 |
4 |
1 |
4 |
=72.8×1,
=72.8;
(4)(
3 |
8 |
1 |
27 |
11 |
27 |
=
3 |
8 |
1 |
27 |
11 |
27 |
=6+
16 |
27 |
11 |
27 |
=6+(
16 |
27 |
11 |
27 |
=6+1,
=7;
(5)24×(
1 |
4 |
1 |
6 |
1 |
3 |
=24×
1 |
4 |
1 |
6 |
1 |
3 |
=6+4-8,
=2;
(6)[
8 |
15 |
2 |
3 |
7 |
15 |
15 |
14 |
=[(
8 |
15 |
2 |
3 |
7 |
15 |
15 |
14 |
=[
8 |
15 |
7 |
15 |
2 |
3 |
15 |
14 |
=
1 |
3 |
15 |
14 |
=
5 |
14 |
点评:此题考查了运四则混合运算,注意运算顺序和运算法则,灵活运用所学的运算定律进行简便计算.
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