题目内容
化简与求值
(1)2
-
+
(2)3
×(
-5
-2
)
(3)计算:
x
-x2
+6x
,其中x=5.
(1)2
18 |
32 |
|
(2)3
8 |
54 |
2 |
6 |
(3)计算:
2 |
3 |
9x |
|
|
(1)原式=6
-4
+
=
;
(2)原式=6
(3
-5
-2
)
=6
(
-5
)
=12
-60;
(3)原式=2x
-x
+3x
=4x
,
当x=5时,原式=4×5×
=20
.
2 |
2 |
| ||
4 |
=
9
| ||
4 |
(2)原式=6
2 |
6 |
2 |
6 |
=6
2 |
6 |
2 |
=12
3 |
(3)原式=2x
x |
x |
x |
=4x
x |
当x=5时,原式=4×5×
5 |
5 |
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