4X+9Z=12 {3Y-2Z=17X+5Z=4又4分之33X-Y+2Z=3{2X+Y-3Z=11X+Y+Z=66

4X+9Z=12 (1)
3Y-2Z=1 (2)
7X+5Z=4又4分之3=19/4 (3)
(1)*5-(3)*9
20X+45Z-63X-45Z=60-9
-43X=51
X=-51/43
Z=(12-4X)/9=80/43
Y=(1+2Z)/3=203/129
3X-Y+2Z=3 (1)
2X+Y-3Z=11 (2)
X+Y+Z=66 (3)
(1)+(2)
5X-Z=14 (4)
(1)+(3)
4X+3Z=69 (5)
(4)*3+(5)
15X-3Z+4X+3Z=42+69
19X=111
X=111/19
Z=5X-14=289/19
Y=66-X-Z=854/19

x=-69/172
y=129/194
z=43/65
x=19/111
y=19/1295
z=-19/60

第一问，x=172分之171，y=387分之359，z=129分之115
第二问，x=19分之111，y=19分之854,z=19分之289

1.x=-69/172 y=173/129 z=65/43
2.x=111/19 y=854/19 z=289/19

1.X=-69/172 y=173/129 z=65/43
2.x=111/19 y=854/19 z=289/19

X=-69/172 Y=173/129 Z=65/43
X=111/19 Y=854/19 Z=289/19