问题 解答题
2
71
+
1
69
)×23+
25
71
2÷7×
2
7
3
5
+
2
5
-
3
5
+
2
5
1
2
×
1
3
+
1
2
×
1
3
5
8
×98+
3
8
×100
17-17×
17
18
答案

(1)(

2
71
+
1
69
)×23+
25
71

=

2
71
×23+
1
69
×
23+
25
71

=(

46
71
+
25
71
+
1
3

=1+

1
3

=1

1
3

(2)2÷7×

2
7

=2×

1
7
×
2
7

=

4
49

(3)

3
5
+
2
5
-
3
5
+
2
5

=(

3
5
-
3
5
)+(
2
5
+
2
5
),

=

4
5

(4)

1
2
×
1
3
+
1
2
×
1
3

=

1
2
×
1
3
×2,

=

1
3

(5)

5
8
×98+
3
8
×100,

=

5
8
×(100-2)+
3
8
×100,

=

5
8
×100-
5
8
×
2+
3
8
×
100,

=(

5
8
+
3
8
)×100-
5
4

=100-

5
4

=98

3
4

(6)17-17×

17
18

=(1-

17
18
)×17,

=

1
18
×17,

=

17
18

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