若(ax²-2xy+y²)-(-ax²+bxy+2y²)=8x²-7xy-cy²成立,则a,b,c的值

若(ax²-2xy+y²)-(-ax²+bxy+2y²)=8x²-7xy-cy²成立,则a,b,c的值
若(ax²-2xy+y²)-(-ax²+bxy+2y²)=8x²-7xy-cy²成立,则a,b,c的值

若(ax²-2xy+y²)-(-ax²+bxy+2y²)=8x²-7xy-cy²成立,则a,b,c的值
解；2aX^2-(2+b)XY-Y^2=8X^2-7XY-cY^2
所以2a=8,2+b=7,1=c
a=4,b=5,c=1