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