М(х; у; z).
A_(1)M=MA_(2)
sqrt((x-3)^2+(y-2)^2+(z-1)^2)=sqrt((x+4)^2+(y+2)^2+(z-1)^2)
(x-3)^2+(y-2)^2+(z-1)^2=(x+4)^2+(y+2)^2+(z-1)^2
(x-3)^2-(x+4)^2+(y-2)^2-(y+2)^2=0
(x-3-x-4)*(x-3+x+4)+(y-2-y-2)*(y-2+y+2)=0
-7*(2x+1)-4*2y=0
14x+8y+7=0
О т в е т. плоскость 14х+8у+7=0