题目内容
脱式计算(能简算的要简算).
|
14.2×24-28.4×2 |
| ||||||||||||||||||
|
4-
|
| ||||||||||||||||||
|
|
|
分析:(1)(4)(6)(8)按照分数加减法的计算方法进行计算即可得到答案;
(2)算式28.4可改写乘14.2×2,然后再按照乘法分配律进行计算即可;
(3)根据算式的特点可利用加法结合律进行计算比较简便;
(5)(7)可分别根据一个数减去若干数,等于这个数减去若干数的和,可把原式改写成4-(
+
)、
-(
+
)进行计算比较简便;
(9)可把原式改写成
+(
-
)进行计算比较简便.
(2)算式28.4可改写乘14.2×2,然后再按照乘法分配律进行计算即可;
(3)根据算式的特点可利用加法结合律进行计算比较简便;
(5)(7)可分别根据一个数减去若干数,等于这个数减去若干数的和,可把原式改写成4-(
7 |
11 |
4 |
11 |
9 |
8 |
5 |
12 |
7 |
12 |
(9)可把原式改写成
17 |
18 |
5 |
8 |
3 |
8 |
解答:解:(1)
+
+
=
+
,
=1
;
(2)14.2×24-28.4×2
=14.2×24-14.2×2×2,
=14.2×(24-4),
=14.2×20,
=284;
(3)
+
+
+
=(
+
)+(
+
),
=1+1,
=2;
(4)
-
-
=
-
,
=0;
(5)4-
-
,
=4-(
+
),
=4-1,
=3;
(6)
-(
+
)
=
-
,
=
;
(7)
-
-
,
=
-(
+
),
=
-1,
=
;
(8)
-(
-
)
=
-
,
=
;
(9)
+
-
=
+(
-
),
=
+
,
=1
.
4 |
5 |
11 |
15 |
3 |
10 |
=
23 |
15 |
3 |
10 |
=1
5 |
6 |
(2)14.2×24-28.4×2
=14.2×24-14.2×2×2,
=14.2×(24-4),
=14.2×20,
=284;
(3)
5 |
6 |
2 |
7 |
1 |
6 |
5 |
7 |
=(
5 |
6 |
1 |
6 |
2 |
7 |
5 |
7 |
=1+1,
=2;
(4)
1 |
2 |
1 |
3 |
1 |
6 |
=
1 |
6 |
1 |
6 |
=0;
(5)4-
7 |
11 |
4 |
11 |
=4-(
7 |
11 |
4 |
11 |
=4-1,
=3;
(6)
9 |
10 |
1 |
2 |
1 |
3 |
=
9 |
10 |
5 |
6 |
=
1 |
15 |
(7)
9 |
8 |
5 |
12 |
7 |
12 |
=
9 |
8 |
5 |
12 |
7 |
12 |
=
9 |
8 |
=
1 |
8 |
(8)
17 |
24 |
5 |
6 |
2 |
3 |
=
17 |
24 |
1 |
6 |
=
13 |
24 |
(9)
17 |
18 |
5 |
8 |
3 |
8 |
=
17 |
18 |
5 |
8 |
3 |
8 |
=
17 |
18 |
1 |
4 |
=1
7 |
36 |
点评:此题主要考查的分数加减法计算方法的应用及其简便计算的应用.
练习册系列答案
相关题目