问题 解答题
(1)计算:-24+20100+2-1+
16
-sin30°

(2)先化简,再求值:(1+
3
a-2
a2-1
2a-4
,其中a=
2
+1
答案

(1)原式=-16+1+

1
2
+4-
1
2
=-9;

(2)原式=

a-2+3
a-2
2(a-2)
(a+1)(a-1)
=
a+1
a-2
2(a-2)
(a+1)(a-1)
=
2
a-1

当a=

2
+1时,原式=
2
2
=
2

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