Question

解方程的解：9x+3y+z=0,x-y+z=0,z=-3

Answer 1

9x+3y+z=0 (1)
x-y+z=0 (2)
z=-3 (3)
(1)+(2)*3
12x+4z=0 (4)
将（3）代入（4）得
12x+4*（-3）=0
x=1
将x=1，z=-3代入（2）得
1-y-3=0
y=-2

不明兆哗白可族悉行追问，满意请采陆梁纳

Answer 2

9x+3y+z=0,x-y+z=0,z=-3
9x+3y=3
x-y=3 (×3+上式渣简戚如陵)
12x=12
x=1
y=-2

所以咐皮解是x=1 y=-2 z=-3

追问

什么意思啊，　　(×3+上式)

追答

9x+3y=3 (i)
x-y=3(ii)
(ii)×3+(i)

Answer 3

9X+3Y-3=0 9X+3Y-3=0 (1) (2)-(1) X=1
X-Y-3=0 9X-9Y-27=0 (2) Y=-2

Answer 4

你好！