问题 解答题
怎样算简便怎样算.
5
9
×
3
4
+
5
9
×
1
4
2
15
+
2
3
×
2
15
答案

(1)

5
9
×
3
4
+
5
9
×
1
4

=

5
9
×(
3
4
+
1
4
),

=

5
9
×1,

=

5
9

(2)

2
15
+
2
3
×
2
15

=1×

2
15
+
2
3
×
2
15

=

2
15
×(1+
2
3
),

=

2
15
×
5
3

=

2
9

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