问题 解答题
小马虎做作业,有一次粗心的他把下面的计算全做错了,请细心的你仔细观察他做错的原因,并帮他改正.
(1)
7
8
+
1
8
×
4
5
=(
7
8
+
1
8
4
5
=1×
4
5
=
4
5

更正:______
(2)72×
5
8
÷72×
5
8

=(72×
5
8
)÷(72×
5
8


=1÷1
=1
更正:______
(3)(
3
5
-
2
7
)×5×7
=
3
5
×5-
2
7×7

=3-2
=1
更正:______
(4)
8
15
÷(
8
15
+
4
5
)

=
8
15
÷
8
15
+
8
15
÷
4
5

=1+
2
3

=1
2
3

更正______.
答案

(1)

7
8
+
1
8
×
4
5

=

7
8
+
1
10

=

39
40

(2)72×

5
8
÷72×
5
8

=(72÷72)×(

5
8
×
5
8
),

=1×

25
64

=

25
64

(3)(

3
5
-
2
7
)×5×7,

=

3
5
×5×7-
2
7
×5×7,

=21-10,

=11;

(4)

8
15
÷(
8
15
+
4
5
),

=

8
15
÷
4
3

=

2
5

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