x-2y-3z=0 2x+y-2z=0 求X:Y:Z的值

问题描述:

x-2y-3z=0 2x+y-2z=0 求X:Y:Z的值

三元一次方程必须有三个方程才能解,除非特殊情况

x-2y-3z=0 ①
2x+y-2z=0 ==> 4x+2y-4z=0 ②
①+2*②==>5x-7z=0 ==>x:z=7:5
x-2y-3z=0 ==> 2x-4y-6z=0 ③
2x+y-2z=0 ④
④-2*③==>5y+4z=0 ==>y:z=-4:5
x:z=7:5
y:z=-4:5
==>x:y:z=7:(-4):5