问题 解答题
(1)计算:
2
1
8
-
1
2
-(
18
+
2
-2
1
3
)

(3
12
-2
1
3
+
48
)÷2
3

(2)解方程:
①3x2+8x-3=0;               
②x-2=x(x-2);
③3x2-4x-2=0(配方法).
答案

(1)①原式=2×

2
4
-
2
2
-(3
2
+
2
-
2
3
3

=

2
2
-
2
2
-3
2
-
2
+
2
3
3

=-4

2
+
2
3
3

②原式=

3
2
4
-
1
9
+
1
2
16

=

3
2
×2-
1
3
+
1
2
×4

=3-

1
3
+2

=4

2
3

(2)①(3x-1)(x+3)=0,

∴3x-1=0或x+3=0,

∴x1=

1
3
,x2=-3;

②(x-2)-x(x-2)=0,

(x-2)(1-x)=0,

∴x-2=0或1-x=0,

∴x1=2,x2=1;

③3x2-4x=2,

变形得:x2-

4
3
x=
2
3

配方得:x2-

4
3
x+
4
9
=
2
3
+
4
9
,即(x-
2
3
2=
10
9

开方得:x-

2
3
10
3

则x1=

2+
10
3
,x2=
2-
10
3

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