{2x-y=7 {y+z=-5 {z-x=-7 三元一次方程

{x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z x+y+z=14 7z=x+y+2 x+z=y x/2=y/3=z/5 x+3y-z/x-3y+z 若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+Z) (x+y-z)(x-y+z)= fangchengzu:X+Z=Y 7Z=X+Y+Z X+Y+Z=14 x+Y+Z=1 X+3Y+7Z=-1 X+5Y+8Z=2x+Y+Z=1X+3Y+7Z=-1X+5Y+8Z=2 用行列式的性质证明：y+z z+x x+y x y z x+y y+z z+x =2 z x y z+x x+y y+z y z x 这个怎么证? 已知x-y/x+y=y+z/2(y-z)=z+x/3(z-x),求证8x+9y+5z=0THX.. (x-2y+z)(x+y-2z)分之（y-x)(z-x) + (x+y-2z)(y+z-2x)分之(z-y)(x-y) + (y+z-2z)(x-2y+z)分之（x-z)(y-z)=?第三部分那个是 （y+z-2x)(x-2y+z)分之（x-z)(y-z) 3x-y=-7,y+2z=2,2x-2z=-5 求x,y,z x+y+z=0,3x-2y-2z=5,y-z=2x-7 X-Y-Z=0 X+Y-3Z=4 2X-5Y+7Z=21 2x+5y+4z=6,3x+y-7z=-4,x+y-z=? 3x+7y+4z=35,x+5y+2z=40,x+y+z=( ) {x+y+z=1 {x+3y+7z=-1 {x+5y+8z=2 {x+y+z=1 {x+3y+7z=2 {x+5y+19z=4