问题
填空题
已知x=
|
答案
xy=（
-1）（3
+1）=3-1=2，3
则原式=x2-xy+xy-y2 (
+y)(x-xy
)xy
=x2-y2 x
+xy-xy-yxy xy
=(x+y)(x-y) (x-y) xy
=
，x+y xy
当x=
-1，y=3
+1时，原式=3
=2 3 2
．6
故答案是：
．6
搜题请搜索小程序“爱下问搜题”
已知x=
|
xy=（
-1）（3
+1）=3-1=2，3
则原式=x2-xy+xy-y2 (
+y)(x-xy
)xy
=x2-y2 x
+xy-xy-yxy xy
=(x+y)(x-y) (x-y) xy
=
，x+y xy
当x=
-1，y=3
+1时，原式=3
=2 3 2
．6
故答案是：
．6