x-4y+z=-302x+y-z=18x--y-z=7

x-4y+z=-302x+y-z=18x--y-z=7 (x+y-z)(x-y+z)= X+Y+Z=? x/y=(x+z)/(y+z)y/z=(x+y)/(x+z) 已知 x/(y+z)+y/(z+x)+z/(x+y)=1求 (x*x)/(y+z)+(y*y)/(x+z)+(z*z)/(x+y)=? (y+z)/x=(z+x)/y=(x+y)/z求x+y-z/x+y+z的值 解方程 x(x+y+z)=6 y(x+y+z)=12 z(x+y+z)=18 解方程组{x(x+y+z)=6,y(x+y+z)=12,z(x+y+z)=18 z+=x>y?++x: x+y/2=z+x/3=y+z/4 x+y+z=27 14x+4y+z=200,x+y+z=100求解x,y,z x+2y=3x+2z=4y+z 求x:y:z 若x,y,z成等差数列,则(z-x)^2-4(x-y)(y-z)= (x*x+2)(y*y+4)(z*z+8)=64xyz,求x,y,z x,y,z不是0.3z=4y,z=3x求（x+y）：（x+z）. 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? fangchengzu:X+Z=Y 7Z=X+Y+Z X+Y+Z=14 x=y; y=z; z=x/y