题目内容
脱式计算,能简算的要简算.
|
(
|
(
| ||||||||||||||||||||
17×(
|
|
分析:(1)先把除法变成乘法,再运用乘法分配律简算;
(2)先运用乘法分配律简算,再运用加法结合律简算;
(3)运用乘法分配律简算;
(4)先把17×15结合在一起,再运用乘法分配律简算;
(5)
=
-
,
=
-
…由此化简求解.
(2)先运用乘法分配律简算,再运用加法结合律简算;
(3)运用乘法分配律简算;
(4)先把17×15结合在一起,再运用乘法分配律简算;
(5)
1 |
5×6 |
1 |
5 |
1 |
6 |
1 |
6×7 |
1 |
6 |
1 |
7 |
解答:解:(1)
÷9+
×
,
=
×
+
×
,
=
×(
+
),
=
×1,
=
;
(2)(
-
)×
+
,
=
×
-
×
+
,
=
-
+
,
=
+(
-
),
=
+
,
=
;
(3)(
-
+
)×48,
=48×
-
×48+
×48,
=24-16+12,
=8+12,
=20;
(4)17×(
+
)×15,
=(17×15)×(
+
),
=(17×
)×15+(15×
)×17,
=2×15+1×17,
=30+17,
=47;
(5)
+
+
+
+
,
=
-
+
-
+
-
+
-
+
-
,
=
-
,
=
.
6 |
25 |
6 |
25 |
8 |
9 |
=
6 |
25 |
1 |
9 |
6 |
25 |
8 |
9 |
=
6 |
25 |
1 |
9 |
8 |
9 |
=
6 |
25 |
=
6 |
25 |
(2)(
1 |
2 |
3 |
7 |
7 |
25 |
18 |
25 |
=
1 |
2 |
7 |
25 |
3 |
7 |
7 |
25 |
18 |
25 |
=
7 |
50 |
3 |
25 |
18 |
25 |
=
7 |
50 |
18 |
25 |
13 |
25 |
=
7 |
50 |
1 |
5 |
=
17 |
50 |
(3)(
1 |
2 |
1 |
3 |
1 |
4 |
=48×
1 |
2 |
1 |
3 |
1 |
4 |
=24-16+12,
=8+12,
=20;
(4)17×(
2 |
17 |
1 |
15 |
=(17×15)×(
2 |
17 |
1 |
15 |
=(17×
2 |
17 |
1 |
15 |
=2×15+1×17,
=30+17,
=47;
(5)
1 |
5×6 |
1 |
6×7 |
1 |
7×8 |
1 |
8×9 |
1 |
9×10 |
=
1 |
5 |
1 |
6 |
1 |
6 |
1 |
7 |
1 |
7 |
1 |
8 |
1 |
8 |
1 |
9 |
1 |
9 |
1 |
10 |
=
1 |
5 |
1 |
10 |
=
1 |
10 |
点评:完成本题要注意分析式中数据,运用合适的简便方法计算.

练习册系列答案
相关题目