Y=4x Y.x都小于Z,Z＝Y＋x-45 Z=?Y=?x=?

Y=4x Y.x都小于Z,Z＝Y＋x-45 Z=?Y=?x=? x=y/z=z/3,x+y+z ＝12,求2x+3y+4z是多少, x-y/(z-x)(z-y) 一y-z/(x-y)(x-z) ＋z-x/(y-z)(y-x) (x+y-z)(x-y+z)= x+y/2=z+x/3=y+z/4 x+y+z=27 x-4y+z=-302x+y-z=18x--y-z=7 14x+4y+z=200,x+y+z=100求解x,y,z x+2y=3x+2z=4y+z 求x:y:z 若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-z)= (x*x+2)(y*y+4)(z*z+8)=64xyz,求x,y,z 已知x,y,z都不小于0,且满足3y+2z=3-x,3y+z=4-3x,若u=3x-2y+4z,求u的最大值求!谢谢了! 已知x,y,z都不小于0,且满足3y+2z=3-x,3y+z=4-3x,若u=3x-2y+4z,求u的最大值 和最小值 已知x、y、z都不为0,且4x-3y-3z=0,x-3y+z=0,求x:y:z x,y,z都>0.且x+y+z=1.求证1/x+4/x+9/z>=36 x,y,z不是0.3z=4y,z=3x求（x+y）：（x+z）. 已知有理数x、y、z满足x＋y/3=y＋z/4＝z＋x/5,且x＋y＋z＝12则x=?y=?z=? (x+y):(y+z):(z+x)=3:4:5 3x+y-z=-4已知(x+y):(y+z):(z+x)=3:4:5 ；3x+y-z=-4求x y z 已知x小于0,y大于0,z小于0,且/x/小于/y/,/y/大于/z/化简/x+z/-/y+z/+/x+y/-/x-y+z/