作业帮设A=2x²-3xy+y²+x-3y,B=4x²-6xy+2y²+4x-y,若|x-3a|+（y+3）²=0,且B-2A=a,求A的值.
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设A=2x²-3xy+y²+x-3y,B=4x²-6xy+2y²+4x-y,若|x-3a|+（y+3）²=0,且B-2A=a,求A的值.
设A=2x²-3xy+y²+x-3y,B=4x²-6xy+2y²+4x-y,若|x-3a|+（y+3）²=0,且B-2A=a,求A的值.
设A=2x²-3xy+y²+x-3y,B=4x²-6xy+2y²+4x-y,若|x-3a|+（y+3）²=0,且B-2A=a,求A的值.
|x-3a|+（y+3）²=0,
|x-3a|＝0,（y+3）²=0,
x=3a,y=-3
B-2A=a
4x²-6xy+2y²+4x-y-2(2x²-3xy+y²+x-3y)=a
4x²-6xy+2y²+4x-y-4x²+6xy-2y²-2x+6y=a
2x+5y=a,因x=3a,y=-3
6a-15=a
a=3
x=9,y=-3
A=2x²-3xy+y²+x-3y=2*81+81+9+9+9=270