已知方程组 5x+8y+z=0
-5x+6y+z=0
求x:y:z=?
已知方程组 5x+8y+z=0
-5x+6y+z=0
求x:y:z=?
5x+8y+z=0
-5x+6y+z=0
两式相加,得:
14y+2z=0
7y+z=0
z=-7y
两式相减,得:
10x+2y=0
5x+y=0
x=-y/5
∴x:y:z = -y/5:y:-7y = -1/5:1:-7 =-1 :5:-35
求x:y:z=?
5x+8x+z+5x-6y-z=0 10x+2y=0 x:y=-1:5
5x+8y+z-5x+6y+z=0 14y+2z=0 y:z=-1:7
15x+24y+3z+20x-24y-4z=0 35x-z=0 x:z=1:35
所以x:y:z=1:-5:35
两个式子相加可以得到 14y+2z=0 ∴y:z=1:(-7)
令y=k 所以 z=-7k
所以带入 5x+8y+z=0 后 5x+8k-8k=0 所以x=0
所以x:y:z=0:1:(-7)
-5x+6y+z=0
z=7Y
X=-Y/5
X;Y;Z= -1;5;35
-5x+6y+z=0
14y+2z=0 7y+z=0 7y=-z
10x+2y=0 5x+y=0 5x=-y -35x=7y
-35x=7y=-z
x:y:z=-1:5:-35