题目内容
(2011?武进区)选择合理的方法进行计算.
(3.8-1.8×0.4)÷0.2
[1.4-(2.4-2.25)]×0.4
÷9+
×
÷[(
+
)×
].
(3.8-1.8×0.4)÷0.2
[1.4-(2.4-2.25)]×0.4
8 |
15 |
1 |
9 |
7 |
15 |
8 |
9 |
2 |
5 |
1 |
10 |
4 |
3 |
分析:(1)先算小括号里面的乘法,再算小括号里面的减法,最后算括号外的除法;
(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)把除法变成乘法,再运用乘法分配律简算;
(4)先算小括号里面的加法,再算中括号里面的乘法,最后算括号外的除法.
(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)把除法变成乘法,再运用乘法分配律简算;
(4)先算小括号里面的加法,再算中括号里面的乘法,最后算括号外的除法.
解答:解:(1)(3.8-1.8×0.4)÷0.2,
=(3.8-0.72)÷0.2,
=3.08÷0.2,
=15.4;
(2)[1.4-(2.4-2.25)]×0.4,
=[1.4-0.15]×0.4,
=1.25×0.4,
=0.5;
(3)
÷9+
×
,
=
×
+
×
,
=(
+
)×
,
=1×
,
=
;
(4)
÷[(
+
)×
],
=
÷[
×
],
=
÷
,
=
×
,
=
.
=(3.8-0.72)÷0.2,
=3.08÷0.2,
=15.4;
(2)[1.4-(2.4-2.25)]×0.4,
=[1.4-0.15]×0.4,
=1.25×0.4,
=0.5;
(3)
8 |
15 |
1 |
9 |
7 |
15 |
=
8 |
15 |
1 |
9 |
1 |
9 |
7 |
15 |
=(
8 |
15 |
7 |
15 |
1 |
9 |
=1×
1 |
9 |
=
1 |
9 |
(4)
8 |
9 |
2 |
5 |
1 |
10 |
4 |
3 |
=
8 |
9 |
1 |
2 |
4 |
3 |
=
8 |
9 |
2 |
3 |
=
8 |
9 |
3 |
2 |
=
4 |
3 |
点评:考查四则混合运算的顺序:1、如果是同一级运算,一般按从左往右依次进行计算;2、如果既有加减、又有乘除法,先算乘除法、再算加减; 3、如果有括号,先算括号里面的; 4、如果符合运算定律,可以利用运算定律进行简算.
练习册系列答案
相关题目