数学2x-y=7 y+z=-5 z-x=-7

数学2x-y=7 y+z=-5 z-x=-7 x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 x+y+z=14 7z=x+y+2 x+z=y (x+y-z)(x-y+z)= x/2=y/3=z/5 x+3y-z/x-3y+z 数学x–y+3z=28 x:y:z=1:2:5 fangchengzu:X+Z=Y 7Z=X+Y+Z X+Y+Z=14 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? (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) 一道六年级数学解三元一次方程组.3x+2y+5z=2x-2y-z=64x+2y-7z=30 数学的三元一次方程x-y-z=-13x+5y+7z=114x-y+2z=-1 若X:Y:Z=5:6:7那么(Y-X):(Y+Z)和(X+2Y+3Z):(3X+2Y+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=1 X+3Y+7Z=-1 X+5Y+8Z=2x+Y+Z=1X+3Y+7Z=-1X+5Y+8Z=2 已知(x+y)(x+z)=x,(y+z)(y+x)=2y,(z+x)(z+y)=3z,求x,y,z 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^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值.