问题
解答题
先化简,再求值:
|
答案
原式=
•x(x+y) (x+y)(x-3y)
+(-(x-3y) x-y
+1 x
)÷(1 y
-1 x
)1 y
=-
+x x-y
•x+y xy xy y-x
=-
+x x-y
.x+y y-x
=-
.2x+y x-y
当x=2,y=-1时,原式=-1.
故答案为-1.
先化简,再求值:
|
原式=
•x(x+y) (x+y)(x-3y)
+(-(x-3y) x-y
+1 x
)÷(1 y
-1 x
)1 y
=-
+x x-y
•x+y xy xy y-x
=-
+x x-y
.x+y y-x
=-
.2x+y x-y
当x=2,y=-1时,原式=-1.
故答案为-1.