试题:
(1)(
3
5
+
2
5
)×15=______×______+______×______
(2)
1
2
×
1
3
+
1
2
×
1
3
=______×(______+______)
(3)(
1
10
+
1
5
)×5=______+______
(4)100×
23
99
=(99+1)×
23
99
=______+______=______.

答案:

我来补答

(1)(
3
5
+
2
5
)×15,
=
3
5
×15+
2
5
×15,
=9+6,
=15;

(2)
1
2
×
1
3
+
1
2
×
1
3

=
1
3
×(
1
2
+
1
2
),
=
1
3
×1,
=
1
3


(3)(
1
10
+
1
5
)×5,
=
1
10
×5+
1
5
×5,
=
1
2
+1,
=1
1
2


(4)100×
23
99

=(99+1)×
23
99

=99×
23
99
+1×
23
99

=23+
23
99

=23
23
99
 
 
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