Question

已知3x-y-3z=0,x-6y=6z=0.则有(x+y+z)/(x-y-z)=_____

Answer 1

3x-y-3z=0,.(1)

x-6y+6z=0.(2)

(1)-(2)*3:

17y-21z=0

y=21/17z

(1)*6-(2):

17x-24z=0

17x=24z

x=24/17z

(x+y+z)/(x-y-z)=(24/17z+21/17z+z)/(24/17z-21/17z-z)=-31/7