问题
解答题
(1)计算:-22+(
(2)先化简,再求值
|
答案
(1)原式=-4+1+2×1 2
=-4+1+1
=-2;
(2)∵x=
,1 2
∴原式=
+(x+1)(x-1) (x-1)2
×x(x-2) x-2
,1 x
=
+1,x+1 x-1
=
+x+1 x-1
,x-1 x-1
=
,2x x-1
=
,2× 1 2
-11 2
=-2.
(1)计算:-22+(
(2)先化简,再求值
|
(1)原式=-4+1+2×1 2
=-4+1+1
=-2;
(2)∵x=
,1 2
∴原式=
+(x+1)(x-1) (x-1)2
×x(x-2) x-2
,1 x
=
+1,x+1 x-1
=
+x+1 x-1
,x-1 x-1
=
,2x x-1
=
,2× 1 2
-11 2
=-2.