已知x+2y-5z=3;x-2y-z=-5,求xx+yy+zz的值
已知14(XX+YY+ZZ)=(X+2Y+3Z)^2,求X:Y:Z
已知x-y=5,y-z=4,求xx+yy+zz-xy-yz-xz的值
已知,x/3 = y/1 = z/2 ,求 2xx - 2yy + 5zz /xy + yz +zx 的值.(/表示分数
x+y+z=5,xx+yy+zz=6,求xy-xz-yz的解
知x/3=y/4=z/5,求(xy+yz+xz)/xx+yy+zz
已知x=1/2 y=1/3 z=1/4 则(xx+yy-zz+2xy)/(xx-yy+zz-2xz) 得多少?
已知X+4Y+3X=3X-2Y-5Z=0(XYZ不等于0),求XY+YZ+2XZ/2XX-3YY+7ZZ的值
若x/3=y/4=z/5,则(xy+yz=xz)/(xx+yy+zz)的值为
已知X+Y+Z=1,且XY+YZ+XZ=0,求XX+YY+ZZ的值?
向量内积问题为什么a(x,y,z)、b(x',y',z')的内积a·b=(xx',yy',zz')=xx'+yy'+zz
已知2x=3y,求xy/xx+yy-yy/xx-yy的值
已知x/4=y/5=z/6 求x+y+z/3x-2y+z的值