x+2y+5=22 4x=y 求x= y= z=

已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z均不为0,求3x*x+2y*y+5z*z/5x*x+y*y- 已知3x=4y,2y=5z,试求x:y:z 3x=4y 2y=5z 试求x:y:z x y z x+y--- = --- = ---- ----y+Z z+x x+y ,求 z 的值 .求 x+y---- 已知3X=4X,5Y=6Z求X+Y：Y+Z (x+y-z)(x-y+z)= 已知2x+5y+4z=6.3x+y-7z=-4 求 x+2y+z 已知2x+5y+4z=6 3x+y-7z=-4求x+y-z 已知x:y:z=3:4:5,3x+2y-4z=18.求：x+y+z. 5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z x/3=y/4=z/5,求x+y+z/3x-2y+z的值, 若x/3=y/4=z/5,求x+y+z/3x-2y+z的值.