若3x-3y-x²+2xy-y²+10=0求x-y

若3x-3y-x²+2xy-y²+10=0求x-y
若3x-3y-x²+2xy-y²+10=0求x-y

若3x-3y-x²+2xy-y²+10=0求x-y
3x-3y-x²+2xy-y²+10=0
3(x-y)-(x-y)²+10=0
(x-y)²-3(x-y)-10=0
[(x-y)-5][(x-y)+2]=0
x-y=5或x-y=-2

等式左边=(x-y)^2-3(x-y)+10=(x-y-5)(x-y+2)=0,所以x-y-5=0或x-y+2=0，即x-y=5或x-y=-2