已知A=2x²-5xy+2y²+x-2y,B=x²-5/2xy+y²-2x+y,且A-2B=3a,|x-a|+(y-1)²=0

已知A=2x²-5xy+2y²+x-2y,B=x²-5/2xy+y²-2x+y,且A-2B=3a,|x-a|+(y-1)²=0
已知A=2x²-5xy+2y²+x-2y,B=x²-5/2xy+y²-2x+y,且A-2B=3a,|x-a|+(y-1)²=0

已知A=2x²-5xy+2y²+x-2y,B=x²-5/2xy+y²-2x+y,且A-2B=3a,|x-a|+(y-1)²=0
A-2B
=2x²-5xy+2y²+x-2y-2x²+5xy-2y²+4x-2y
=5x-4y=3a
|x-a|+(y-1)²=0
所以x-a=0,y-1=0
x=a,y=1
代入5x-4y=3a
5a-4=3a
a=2
x=2,y=1