问题
解答题
| 计算： ①
②
|
答案
①原式=
•a+2 (a-1)2
•(a-2)2 a+1 (a+1)(a-1) (a+2)(a-2)
=
；a-2 a-1
②原式=
-x2 xy
+y2 xy x2+y2 xy
=x2-y2+x2+y2 xy
=
．2x y
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| 计算： ①
②
|
①原式=
•a+2 (a-1)2
•(a-2)2 a+1 (a+1)(a-1) (a+2)(a-2)
=
；a-2 a-1
②原式=
-x2 xy
+y2 xy x2+y2 xy
=x2-y2+x2+y2 xy
=
．2x y