题目内容
计算
(1)(3
+
-4
)÷
(2)先化简,再求值:
-
,且a=
.
(1)(3
18 |
1 |
5 |
50 |
|
32 |
(2)先化简,再求值:
1-2a+a2 |
a-1 |
| ||
a2-a |
1 | ||
2+
|
(1)原式=(9
+
-2
)÷(4
)
=8
÷4
=2;
(2)原式=
-
=a-1+
当a=
时,
原式=
-1+2+
=2-
-1+2+
=3.
2 |
2 |
2 |
2 |
=8
2 |
2 |
=2;
(2)原式=
(a-1)2 |
a-1 |
| ||
a(a-1) |
=a-1+
1 |
a |
当a=
1 | ||
2+
|
原式=
1 | ||
2+
|
3 |
=2-
3 |
3 |
=3.
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