题目内容
解下列各题:
(1)(
-2
)×
-6
+
(2)
+
+
-15
(3)已知
=x,
=2,z是9的平方根,求:2x+y-5z的值.
(1)(
6 |
15 |
3 |
|
7 | ||
|
(2)
12 |
27 |
1 |
4 |
48 |
|
(3)已知
25 |
y |
(1)原式=
-2
-3
+
=3
-6
-3
+
=-6
+
;
(2)原式=2
+3
+
-5
=
;
(3)∵
=x,
=2,z是9的平方根,
∴x=5,y=4,z=±3
当x=5,y=4,z=3时,2x+y-5z=2×5+4-5×3=-1;
当x=5,y=4,z=-3时,2x+y-5z=2×5+4-5×(-3)=29.
6×3 |
15×3 |
2 |
| ||
2 |
2 |
5 |
2 |
| ||
2 |
5 |
| ||
2 |
(2)原式=2
3 |
3 |
3 |
3 |
3 |
(3)∵
25 |
y |
∴x=5,y=4,z=±3
当x=5,y=4,z=3时,2x+y-5z=2×5+4-5×3=-1;
当x=5,y=4,z=-3时,2x+y-5z=2×5+4-5×(-3)=29.
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