若x2-2x+y2+6y+10=0,则x-y=_.

问题描述:

若x2-2x+y2+6y+10=0,则x-y=______.

原式可化为:x2-2x+1+y2+6y+9=0,(x-1)2+(y+3)2=0,则x-1=0,x=1;y+3=0,y=-3.x-y=1-(-3)=4.