x²+y²-6x+2y+|z+3|+10=0
(x²-6x+9)+(y²+2y+1)+|z+3|=0
(x-3)²+(y+1)²+|z+3|=0
平方项与绝对值项均恒非负,三个非负项之和=0,三个非负项都=0
x-3=0 x=3
y+1=0 y=-1
z+3=0 z=-3
x+z-y=3+(-3)-(-1)=1