题目内容
用简便方法计算.
| (
| ||||||||||||
|
|
(1)
×
×
=
×
=
;
(2)(
-
)×
=
×
-
×
=
-
=
;
(3)
×
+
×
=(
+
)×
=1×
=
;
(4)
×29+
=
×(29+1)
=
×30
=23.
| 5 |
| 7 |
| 14 |
| 15 |
| 3 |
| 8 |
=
| 2 |
| 3 |
| 3 |
| 8 |
=
| 1 |
| 4 |
(2)(
| 1 |
| 3 |
| 1 |
| 9 |
| 27 |
| 31 |
=
| 1 |
| 3 |
| 27 |
| 31 |
| 1 |
| 9 |
| 27 |
| 31 |
=
| 9 |
| 31 |
| 3 |
| 31 |
=
| 6 |
| 31 |
(3)
| 8 |
| 9 |
| 3 |
| 4 |
| 1 |
| 9 |
| 3 |
| 4 |
=(
| 8 |
| 9 |
| 1 |
| 9 |
| 3 |
| 4 |
=1×
| 3 |
| 4 |
=
| 3 |
| 4 |
(4)
| 23 |
| 30 |
| 23 |
| 30 |
=
| 23 |
| 30 |
=
| 23 |
| 30 |
=23.
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