4X+9Z=12
问题描述：
4X+9Z=12
{3Y-2Z=1
7X+5Z=4又4分之3
3X-Y+2Z=3
{2X+Y-3Z=11
X+Y+Z=66
答
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