已知x+y=7,xy=-8,求xx+yy
已知2x=3y,求xy/xx+yy-yy/xx-yy的值
已知x(x+1)-(xx+y)=3,求(xx+yy)/2-xy的值
已知x,y是实数,且适合方程(xx+xy-12)(xx+xy-12)+(xy-2yy-1)(xy-2yy-1)=0求x,
已知(x+y)(x+y)=25,(x-y)(x-y)=9求xy与xx+yy的值
已知XX+YY=7 XY=-2 X= Y=?
x(x+1)-(xx+y)=-3,求(xx+yy)/2-xy的值
已知xx+yy+4x-6y+13=0,求(xx-2x)/xx+3yy的值.
已知x-y=5,y-z=4,求xx+yy+zz-xy-yz-xz的值
已知X+Y+Z=1,且XY+YZ+XZ=0,求XX+YY+ZZ的值?
已知:xx-xy=7,xy-yy=4,则xx-yy=( )
知x/3=y/4=z/5,求(xy+yz+xz)/xx+yy+zz
x+y+z=5,xx+yy+zz=6,求xy-xz-yz的解