题目内容
计算
(1)
+
+
+(-
)-1
(2)先化简,再求值:(
-
)÷
,其中a=-1.
(1)
(-5)2 |
-3 | ||
|
-20 |
0.2 |
| ||
3 |
(2)先化简,再求值:(
3a |
a-1 |
a |
a+1 |
a |
a2-1 |
(1)原式=5+
-
+
=5-1-5-
=-1-
;
(2)原式=
•
-
•
=3(a+1)-(a-1)
=3a+3-a+1
=2a+4.
-3 |
2+1 |
1 |
0.2 |
1 | ||||
-
|
=5-1-5-
3 |
=-1-
3 |
(2)原式=
3a |
a-1 |
(a-1)(a+1) |
a |
a |
a+1 |
(a-1)(a+1) |
a |
=3(a+1)-(a-1)
=3a+3-a+1
=2a+4.
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