问题 填空题
已知-1<a<0,化简
(a+
1
a
)
2
-4
(a-
1
a
)
2
+4
得______
答案

∵-1<a<0,

∴a+

1
a
<0,a-
1
a
>0;

(a+
1
a
)
2
-4
(a-
1
a
)
2
+4
=
(a-
1
a
)
2
(a+
1
a
)
2

=(a-

1
a
)[-(a+
1
a
)]

=-a2+

1
a2

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