问题
解答题
计算:(1)
(2)先化简,再求值.
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答案
(1)原式=
(2×2
-1)+1-2 2 1
-12
=
(2
-1)+1-2
-12
=2-
+1-2
-12
=2-2
;2
(2)原式=
×x-5 (x+3)(x-3)
+(x+3)2 (x+3)(x-5) 1 x-3
=
+1 x-3 1 x-3
=
,2 x-3
∵x=
+2,3
∴原式=
=2 x-3
=2
+2-33
=2
-13
+1.3