已知{4x-3y-6z=0 x+2y-7z=0,并且z≠0 （1）求x:y (2)求x:y:z

(1)4x-3y-6z=0①x+2y-7z=0②①×7-②×6→22x-33y=0所以x:y=3:2(2) x=3y/2③ 代入②中3y/2+2y-7z=07y/2=7zz=y/2④所以x:y:z=3y/2:y:y/2=3/2:1:1/2=3:2:1(3) x=3z,y=2z 代入2x²+3y²+6z²）\(x²+5y...