题目内容
用简便方法计算．
| (
|
| ||||||||||||||||||
(
| 20
| 14
|
（1）
÷
÷
=
×
×
=2；
（2）（
+
）÷
=（
+
）×
=
×
+
×
=
+
=
；
（3）
÷
×
=
×
×
=
；
（4）（
-
）÷
=（
-
）×
=
×
-
×
=
-
=
；
（5）20
÷
-
÷
=（20
-
）÷
=20×
=25；
（6）14
÷14
=（14+
）×
=14×
+
×
=1+
=1
．
| 15 |
| 16 |
| 5 |
| 8 |
| 3 |
| 4 |
=
| 15 |
| 16 |
| 8 |
| 5 |
| 4 |
| 3 |
=2；
（2）（
| 4 |
| 9 |
| 8 |
| 21 |
| 2 |
| 3 |
=（
| 4 |
| 9 |
| 8 |
| 21 |
| 3 |
| 2 |
=
| 4 |
| 9 |
| 3 |
| 2 |
| 8 |
| 21 |
| 3 |
| 2 |
=
| 2 |
| 3 |
| 4 |
| 7 |
=
| 26 |
| 21 |
（3）
| 8 |
| 9 |
| 5 |
| 7 |
| 15 |
| 14 |
=
| 8 |
| 9 |
| 7 |
| 5 |
| 15 |
| 14 |
=
| 4 |
| 3 |
（4）（
| 9 |
| 10 |
| 3 |
| 15 |
| 3 |
| 5 |
=（
| 9 |
| 10 |
| 1 |
| 5 |
| 5 |
| 3 |
=
| 9 |
| 10 |
| 5 |
| 3 |
| 1 |
| 5 |
| 5 |
| 3 |
=
| 3 |
| 2 |
| 1 |
| 3 |
=
| 7 |
| 6 |
（5）20
| 7 |
| 9 |
| 4 |
| 5 |
| 7 |
| 9 |
| 4 |
| 5 |
=（20
| 7 |
| 9 |
| 7 |
| 9 |
| 4 |
| 5 |
=20×
| 5 |
| 4 |
=25；
（6）14
| 7 |
| 9 |
=（14+
| 7 |
| 9 |
| 1 |
| 14 |
=14×
| 1 |
| 14 |
| 7 |
| 9 |
| 1 |
| 14 |
=1+
| 1 |
| 18 |
=1
| 1 |
| 18 |
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