题目内容
计算下面各题. 15÷
|
25-
| ||||||||||||||||
(
|
(
| ||||||||||||||||
|
[1-(
|
分析:(1)(5)把除法改为乘法,约分计算;
(2)先算除法,再算加法;
(3)先算括号内的除法,再算括号内的加法,最后算括号外的乘法;
(4)两个括号同时计算,最后算除法;
(6)先算小括号内的,再算中括号内的,最后算括号外的.
(2)先算除法,再算加法;
(3)先算括号内的除法,再算括号内的加法,最后算括号外的乘法;
(4)两个括号同时计算,最后算除法;
(6)先算小括号内的,再算中括号内的,最后算括号外的.
解答:解:(1)15÷
÷
,
=15×
×
,
=10
;
(2)25-
÷
,
=25-
×
,
=25-10,
=15;
(3)(
+
÷
)×
,
=(
+
×
)×
,
=(
+
)×
,
=1×
,
=
;
(4)(
-
)÷(
+
),
=
÷
,
=
×
,
=
;
(5)
÷3×
,
=
×
×
,
=
;
(6)[1-(
+
)]÷
,
=[1-
]×4,
=
×4,
=
.
5 |
4 |
8 |
7 |
=15×
4 |
5 |
7 |
8 |
=10
1 |
2 |
(2)25-
12 |
5 |
6 |
25 |
=25-
12 |
5 |
25 |
6 |
=25-10,
=15;
(3)(
3 |
5 |
4 |
25 |
2 |
5 |
1 |
3 |
=(
3 |
5 |
4 |
25 |
5 |
2 |
1 |
3 |
=(
3 |
5 |
2 |
5 |
1 |
3 |
=1×
1 |
3 |
=
1 |
3 |
(4)(
3 |
5 |
2 |
15 |
1 |
12 |
5 |
6 |
=
7 |
15 |
11 |
12 |
=
7 |
15 |
12 |
11 |
=
28 |
55 |
(5)
12 |
17 |
4 |
5 |
=
12 |
17 |
1 |
3 |
4 |
5 |
=
16 |
85 |
(6)[1-(
1 |
4 |
3 |
8 |
1 |
4 |
=[1-
5 |
8 |
=
3 |
8 |
=
3 |
2 |
点评:此题考查了分手肚饿四则混合运算,注意运算顺序和运算法则.
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