{x+y=10 2x-3y+2z=5 x+2y-z=3急啊!
x/2=y/3=z/5 x+3y-z/x-3y+z
试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y)
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
已知x/3=y/5=z/4,求x+y+z/y和x+y-z/y-x的值,2种方法.急等.
1.已知x:y:z=4:5:7,求:(一)2x+3y+z/5z; (二)x+y/y+z 非常急,
3x+2y+z=14 ,x+y+z=10,z+2x+3y=1 5
{2x+3y-4z=-5 x+y+z=6 x-y+3z=10
已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3
200分求数学题,急x+y-z=-14x-3y+2z=162x-2y-3z=5求z等于多少
2X+Y+Z=10,X+2Y+Z=-6,X+Y+2Z=8 5X+4Y-3Y=13,2X-3Y+7Z=19,3X-Y=2X
若4x-3y-6z=0,x+2y-7z=0,求代数式5x*5x+2y*2y-z*z/2x*2x-3y*3y-10z*10
已知x、y、z满足2x+3y+z=48 x-2y+2z=56 3x+5y+3z=52 则x+y+z的值为多少 急