问题 解答题
化简求值:当a=
1
2
-1
,b=
1
2
+1
时,求a2+4ab+b2
答案

a=

1
2
-1
=
2
+1
(
2
-1)(
2
+1)
=
2
+1,

  b=

1
2
+1
=
2
-1
(
2
+1)(
2
-1)
=
2
-1,

原式=(a+b)2+2ab,

=(2

2
2+2(
2
+1)(
2
-1),

=8+2,

=10.

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