4X-5Y+2Z=1,8X-3Y-Z=15,5X+2Y-3Z=18

问题描述:

4X-5Y+2Z=1,8X-3Y-Z=15,5X+2Y-3Z=18

4X-5Y+2Z=1,⑴
8X-3Y-Z=15,⑵
5X+2Y-3Z=18 ⑶
⑵×2+⑴
20x-11y=31⑷
⑵×3-⑶
19x-11y=27⑸
⑷-⑸得:x=4
将x=4代入⑶得:20*4-11y=31,y=49/11
将x=4,y=49/11代入⑵得:8*4-3*49/11-z=15
z=40/11
x=4
y=49/11
z=40/11