问题 解答题
(1)计算:-22+(
1
2
-1
)
0
+2sin30°         
 (2)先化简,再求值
x2-1
x2-2x+1
+
x2-2x
x-2
÷x
,其中x=
1
2
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

=

x+1
x-1
+1,

=

x+1
x-1
+
x-1
x-1

=

2x
x-1

=

1
2
1
2
-1

=-2.

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