X+Y+Z=200,1/3X+4Y+5Z=200,求X,Y,Z等于多少?Z是三个大于0的整数，无解说明下原因，谢谢（是（1/3）X）三分之一X

x-y+z=-1 5x+2y-z=6 4x-3y+2z=-5 x+y+z=-5,3x+y+z=1,4x+3y+2z=-2快 3x-y+2z=-1 4x+y+z=5 x-2y-z=-2 x+y+z=-1 4x-2y+3z=5 y-z=8-2x x+y+z=1 4x+5y-z=6 x+2y-z=3 {x+y+z=1 {x+3y+7z=2 {x+5y+19z=4 1.{x:y:z=3:4:5 2x+3y-5z=-142.{x-y-z=-1 3x+5y+7z=11 4x-y+2z=-13.{x+y=1 x+z=0 2x+y+2z=44.{x-y+z=-3 2x-y-z=-2 -3x+y+z=-15.{x-y+z=-3 3x+y-4z=6 2x+y-z=36.{x-2y+5z=16 2x+y-5z=7 2x-y+z=38 (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 x-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 分别求出x=?y=?z=? 三元一次方程 X-y-z=-1 3x+5y+7z=11 4x-y+2z=-1 X=?Y=?Z=? x,y,z属于正实数,且3x+4y+5z=1 求1/(x+y)+1/(y+z)+1/(x+z)的最小值 已知x:：y：z=3：4：5,(1)求x+y分之z的值；（2）若x+y+z=6,求x,y,z. x+2y-z=-5 x+y+2z=-1 3x+4y-2z=-12x+2y-z=3 2x+y+3z=0 4x+z=-4 解三元一次方程组1、x+y-z=4 2x-y+z=5 x-3y+z=-2 2、y+2z=-2 3x+y-4z=1 2x-y+2z=8 3、x-2y+z=-1 x+y+z=2x+2y+3z=-1 {5x-3y+z=2{5x+2y-4z=3{-5x+y-z=2 {x-y-z=-1{3x+5y+7z{4x-y+2x=-1 (4x-2y-z)-{5x-[8y-2z-(x-2y)]-x-(3y-10z)}=? 已知x:y:z=4:5:7,求:(1)2x+3y+z/5z; (2)x+y/y+z. 三元一次方程组解法 4x+y-z=12 x+y+z=26 3x+2y+z=-5 x-y=1 x-y+5z=1 2x-y+z=18 急 急、、、、、、、、、、