(x+1)/3=(y-1)/22x+2=3y-3y=2x/3+5/3过M垂直y=2x/3+5/3 y-1=-1/(2/3) (x-2) y=4-3x/2(x+1)/3=z/-13z=-x-1,z=-x/3-1/3过M垂直z=-x/3-1/3 z-3=-1/(-1/3) (x-2) z=3x-3过M垂直直线L:(4-y)+(z+3)/2=3x8-2y+z+3=6xx+2y-z-11=0