已知X、Y、Z满足2X-Y+4Z=8(1);X-2Y-Z=7(2)求X-Y-Z的值

问题描述:

已知X、Y、Z满足2X-Y+4Z=8(1);X-2Y-Z=7(2)求X-Y-Z的值

2x-y+4z=8.1
x-2y-z=7.2
1+2,得:
3x-3y+3z=15
即:x-y+z=5