x+2y-z=6 2x+y+z=9 3x+4y+z=18 解方程组

试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. x+y+z=6 x+2y+3z=14 y+1=z X/10=Y/8=Z/9,则X+Y+Z/2Y-3Z 三元一次方程x+y+z=0 4x+2y+z=3 9x+3y+z=6x+y+z=04x+2y+z=3 9x+3y+z=6 x=2y-9z x+2y-3z=2 x-2y+6z=1 方程组3x+y+2z=10,2x+3y-z=9,x+y+z=6 {x+y+z=0 {4x+2y+z=3 {9x+2y+z=6 方程组3x-y-z=9,2x+y-2z=6,x+y+z=15 {x+y+z=0 4x+2y+z=3 9x+3y+z=6 {x+y+z=6,2x-y+z=3,3x+9y+z=24 x+y+z+2,4x+2y+z+2,9x+3y+z=6解方程组 如果|x+y+z-6|+|2x+3y-z-12|+|2x-y-z|=0求x,y, 三元一次方程组,1.x-2y+z=9 2x+y+3z=10 3x+2y1.x-2y+z=92x+y+3z=103x+2y-z2.3x-5y+2z=14x+5y-z=5X-5y+3z=-23.7x+2y-z=76x-y+z=74x+3y+z=94.4x+3y-2z=-75x-6y+z=12x+z=-25.2x+3y-4z=-23x-2y+5z=262x+5z=31 9x-5y+z=-6 9x+y-2z=3 -9x+3y-5z=0 求x y z 6x+3y-2z=108,9x+7y-3z=212,3x-2y+5z=38,求x,y,z 证明 ：x/(y+z)+y/(z+x)+z/(x+y)>=3/2其中 x,y,z>0