问题
解答题
先化简,再求值:(
|
答案
(
)(x2-4y2 x2+4xy+4y2
+x)4xy x-2y
=
•(x+2y)(x-2y) (x+2y)2 x(x+2y) x-2y
=x,
当x=
-1,y=2
+1时,原式=x=2
-1.2
先化简,再求值:(
|
(
)(x2-4y2 x2+4xy+4y2
+x)4xy x-2y
=
•(x+2y)(x-2y) (x+2y)2 x(x+2y) x-2y
=x,
当x=
-1,y=2
+1时,原式=x=2
-1.2