>
数学
>
已知
a
=
1
2+
3
,
b
=
1
2−
3
,则
a
2
−
b
2
2
a
+2
b
= ___ .
人气:264 ℃ 时间:2020-02-03 18:05:43
解答
a
2
-
b
2
2a+2b
=
(a+b)(a-b)
2(a+b)
=
a-b
2
.
因为
a=
1
2+
3
,b=
1
2-
3
,
所以a=2-
3
,b=2+
3
.
∴原式=
2-
3
-2-
3
2
=-
3
.
故应填:-
3
.
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