已知4x-3y+6z=0 x+2y-7z=0 则x-y+z/x+y-z=?

4x-3y+6z=0 ...(1)x+2y-7z=0 ...(2)由(1)式+(2)式,可得:5x=y+z ...(3)把(2)再代到(1)中,可得:4(7z-2y)-3y+6z=0即11y-34z=0 ...(4)再将(3)左右同乘以11.5,得:11.5y+11.5z=57.5x ...(5) 由(4)式+(5)式,得:22.5y-22.5z=...