2x+5y+4z=6,3x+y-7z=-4,x+y

2x+5y+4z=6,3x+y-7z=-4,x+y-z=?

1个回答

已知,2x+5y+4z = 6 ,3x+y-7z = -4 ,
可得：2(2x+5y+4z)+3(3x+y-7z) = 2*6+3*(-4) = 0 ；
即有：13(x+y-z) = 0 ,
所以,x+y-z = 0 .