题目内容
计算或解方程
①
+3
-
+
;
②(2-
)2005(2+
)2006;
③3(x-2)2=x(x-2);
④
x2-
x-
=0.
①
8 |
|
1 | ||
|
| ||
2 |
②(2-
5 |
5 |
③3(x-2)2=x(x-2);
④
1 |
2 |
1 |
3 |
1 |
6 |
①
+3
-
+
=2
+
-
+
=
+
.
②(2-
)2005(2+
)2006
=[(2-
)(2+
)]2005•(2+
)
=(4-5)2005•(2+
)
=-(2+
)
=-2-
.
③3(x-2)2=x(x-2)
3(x-2)2-x(x-2)=0
(x-2)[3(x-2)-x]=0
(x-2)(2x-6)=0
∴x-2=0或2x-6=0
∴x1=2,x2=3.
④
x2-
x-
=0
3x2-2x-1=0
(3x+1)(x-1)=0
3x+1=0或x-1=0
∴x1=-
,x2=1.
8 |
|
1 | ||
|
| ||
2 |
=2
2 |
3 |
| ||
2 |
| ||
2 |
=
3
| ||
2 |
3
| ||
2 |
②(2-
5 |
5 |
=[(2-
5 |
5 |
5 |
=(4-5)2005•(2+
5 |
=-(2+
5 |
=-2-
5 |
③3(x-2)2=x(x-2)
3(x-2)2-x(x-2)=0
(x-2)[3(x-2)-x]=0
(x-2)(2x-6)=0
∴x-2=0或2x-6=0
∴x1=2,x2=3.
④
1 |
2 |
1 |
3 |
1 |
6 |
3x2-2x-1=0
(3x+1)(x-1)=0
3x+1=0或x-1=0
∴x1=-
1 |
3 |
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