题目内容
脱式计算.
48×(
| (
| 319×
| ||||||||||||||||||||||
| [
|
|
考点:分数的四则混合运算,分数的简便计算
专题:运算顺序及法则,运算定律及简算
分析:(1)(2)(3)利用乘法分配律简算;
(4)先算加法,再算除法;
(5)先算减法,再算除法,最后算乘法;
(6)先算加法,再算乘法,最后算除法.
(4)先算加法,再算除法;
(5)先算减法,再算除法,最后算乘法;
(6)先算加法,再算乘法,最后算除法.
解答:
解:(1)48×(
-
)
=48×
-48×
=40-18
=22;
(2)(
-
)÷
=(
-
)×
=
×
-
×
=
-
=
;
(3)319×
+
×319
=319×(
+
)
=319×1
=319;
(4)
÷(
+
)
=
×
=
;
(5)[
÷(
-
)]×
=[
×
]×
=
×
=
;
(6)
÷[(
+
)×
]
=
÷[
×
]
=
×4
=
.
5 |
6 |
3 |
8 |
=48×
5 |
6 |
3 |
8 |
=40-18
=22;
(2)(
2 |
3 |
2 |
5 |
8 |
15 |
=(
2 |
3 |
2 |
5 |
15 |
8 |
=
2 |
3 |
15 |
8 |
2 |
5 |
15 |
8 |
=
5 |
4 |
3 |
4 |
=
1 |
2 |
(3)319×
5 |
9 |
4 |
9 |
=319×(
5 |
9 |
4 |
9 |
=319×1
=319;
(4)
5 |
12 |
2 |
3 |
1 |
4 |
=
5 |
12 |
12 |
11 |
=
5 |
11 |
(5)[
7 |
15 |
3 |
4 |
2 |
5 |
1 |
4 |
=[
7 |
15 |
20 |
7 |
1 |
4 |
=
4 |
3 |
1 |
4 |
=
1 |
3 |
(6)
5 |
16 |
1 |
2 |
1 |
6 |
3 |
8 |
=
5 |
16 |
2 |
3 |
3 |
8 |
=
5 |
16 |
=
5 |
4 |
点评:分数混合运算的关键是抓住运算顺序,正确运用运算定律简算.
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