问题
解答题
(1)计算: ①2
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
-(32 2
+2
-2 2 3
)3
=
-2 2
-32 2
-2
+2 2 3 3
=-4
+2 2 3
;3
②原式=3 2
-4
+1 9 1 2 16
=
×2-3 2
+1 3
×41 2
=3-
+21 3
=4
;2 3
(2)①(3x-1)(x+3)=0,
∴3x-1=0或x+3=0,
∴x1=
,x2=-3;1 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-
x=4 3
,2 3
配方得:x2-
x+4 3
=4 9
+2 3
,即(x-4 9
)2=2 3
,10 9
开方得:x-
=±2 3
,10 3
则x1=
,x2=2+ 10 3
.2- 10 3