(1)解方程:2x2-2x-1=0; (2)先化简后求值:(
|
(1)原方程变为:(x-
)2=1 2
(2分)3 4
∴x1=
,x2=1+ 3 2
.(4分)1- 3 2
(用求根公式法解答可参照给分)
(2)原式=
×x+1-2(x-2) x2-4
(1分)x+2 x-5
=
(3分)1 2-x
将x=
+2代入得,原式=2
=-1 2-(2+
)2
.(4分)2 2
(1)解方程:2x2-2x-1=0; (2)先化简后求值:(
|
(1)原方程变为:(x-
)2=1 2
(2分)3 4
∴x1=
,x2=1+ 3 2
.(4分)1- 3 2
(用求根公式法解答可参照给分)
(2)原式=
×x+1-2(x-2) x2-4
(1分)x+2 x-5
=
(3分)1 2-x
将x=
+2代入得,原式=2
=-1 2-(2+
)2
.(4分)2 2