题目内容
下面各题,怎样简便就怎样算:
(
|
|
| ||||||||||||||||
(
|
| 3÷
|
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)运用乘法分配律简算;
(2)先算小括号里面的减法,再算中括号里面的减法,最后算括号外的乘法;
(3)运用乘法分配律简算;
(4)先同时运算两个小括号里面的加法,再算括号外的除法;
(5)先把除法变成乘法,再运用乘法分配律简算;
(6)按照从左到右的顺序计算.
(2)先算小括号里面的减法,再算中括号里面的减法,最后算括号外的乘法;
(3)运用乘法分配律简算;
(4)先同时运算两个小括号里面的加法,再算括号外的除法;
(5)先把除法变成乘法,再运用乘法分配律简算;
(6)按照从左到右的顺序计算.
解答:
解:(1)(
+
-
)×24
=
×24+
×24-
×24
=14+4-5
=13;
(2)
×[1-(
-
)]
=
×[1-
]
=
×
=
;
(3)
×59+
×41
=
×(59+41)
=
×100
=12.5;
(4)(
+
)÷(3+
)
=
÷
=
;
(5)
÷23+
×
=
×
+
×
=(
+
)×
=1×
=
;
(6)3÷
÷
÷4
=9÷
÷4
=12÷4
=3.
7 |
12 |
1 |
6 |
5 |
24 |
=
7 |
12 |
1 |
6 |
5 |
24 |
=14+4-5
=13;
(2)
4 |
29 |
3 |
4 |
3 |
8 |
=
4 |
29 |
3 |
8 |
=
4 |
29 |
5 |
8 |
=
5 |
58 |
(3)
1 |
8 |
1 |
8 |
=
1 |
8 |
=
1 |
8 |
=12.5;
(4)(
1 |
3 |
1 |
2 |
2 |
3 |
=
5 |
6 |
11 |
3 |
=
5 |
22 |
(5)
8 |
17 |
1 |
23 |
9 |
17 |
=
8 |
17 |
1 |
23 |
1 |
23 |
9 |
17 |
=(
8 |
17 |
9 |
17 |
1 |
23 |
=1×
1 |
23 |
=
1 |
23 |
(6)3÷
1 |
3 |
3 |
4 |
=9÷
3 |
4 |
=12÷4
=3.
点评:此题是考查四则混合运算,要仔细观察算式的特点,灵活运用一些定律进行简便计算.
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