fangchengzu:X+Z=Y 7Z=X+Y+Z X+Y+Z=14

fangchengzu:X+Z=Y 7Z=X+Y+Z X+Y+Z=14 (x+y-z)(x-y+z)= x+y-z=3 y+z-x=5 z+x-y=7 求x,y,z x-4y+z=-302x+y-z=18x--y-z=7 x+y+z=14 7z=x+y+2 x+z=y X+Y+Z=? x/y=(x+z)/(y+z)y/z=(x+y)/(x+z) {x+y+z=1;x+3y+7z=-1;z+5y+8z=-2 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)=? x+y=100,85%x+75%y=81fangchengzu X/4=Y/5=Z/7则x+y+z/z=? (y+z)/x=(z+x)/y=(x+y)/z求x+y-z/x+y+z的值 z=x^(y/z) 偏导数 求Y(Z)=Z(Z+2)/(3Z-7)(Z+1)的z反变换 (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) 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? 设z=z(x,y)由方程φ(x/z,y/z) 确定,证明x*∂z/∂x+y*∂z/∂y=z x+Y+Z=1 X+3Y+7Z=-1 X+5Y+8Z=2x+Y+Z=1X+3Y+7Z=-1X+5Y+8Z=2