题目内容
脱式计算,能简算的要简算. ①(
|
②
|
③
| ||||||||||||||||||||||
④(9.5+
|
⑤[
|
⑥(
|
分析:算式①③⑥可根据乘法分配律进行计算;
算式②⑤根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
算式④可将式中的分数化为小数后再进行计算.
算式②⑤根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的;
算式④可将式中的分数化为小数后再进行计算.
解答:解:①(
+
-
)×24
=
×24+
×24-
×24,
=8+2-4,
=6;
②
×
+
÷
=
+
×
,
=
+
,
=
;
③
×
+
×
=(
+
)×
,
=1×
,
=
;
④(9.5+
)-(2.8-
)
=(9.5+0.6)-(2.8-0.4),
=10.1-2.4,
=7.7;
⑤[
-(
-
)]÷
=[
-(
-
)]×
,
=[
-
]×
,
=
×
,
=
;
⑥(
+
)×
=
×
+
×
,
=
+
,
=
+
,
=
.
1 |
3 |
1 |
12 |
1 |
6 |
=
1 |
3 |
1 |
12 |
1 |
6 |
=8+2-4,
=6;
②
4 |
5 |
2 |
3 |
1 |
5 |
3 |
4 |
=
8 |
15 |
1 |
5 |
4 |
3 |
=
8 |
15 |
4 |
15 |
=
4 |
5 |
③
2 |
7 |
8 |
9 |
5 |
7 |
8 |
9 |
=(
2 |
7 |
5 |
7 |
8 |
9 |
=1×
8 |
9 |
=
8 |
9 |
④(9.5+
3 |
5 |
2 |
5 |
=(9.5+0.6)-(2.8-0.4),
=10.1-2.4,
=7.7;
⑤[
1 |
2 |
3 |
4 |
3 |
5 |
7 |
10 |
=[
1 |
2 |
15 |
20 |
12 |
20 |
10 |
7 |
=[
10 |
20 |
3 |
20 |
10 |
7 |
=
7 |
20 |
10 |
7 |
=
1 |
2 |
⑥(
5 |
7 |
5 |
8 |
2 |
5 |
=
5 |
7 |
2 |
5 |
5 |
8 |
2 |
5 |
=
2 |
7 |
1 |
4 |
=
8 |
28 |
7 |
28 |
=
15 |
28 |
点评:完成有关于分数的四则混合运算时要细心,注意通分约分.
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