已知XX—XY=5,XY—YY=-3,求代数式XX—YY和XX—2XY+YY
已知2x=3y,求xy/xx+yy-yy/xx-yy的值
已知(XX+YY—2)(XX+YY)=3,求XX+YY
已知xx+xy=1,xy-yy=-4,则xx+2xy-yy=
3xx+xy+yy=15
已知x(x+1)-(xx+y)=3,求(xx+yy)/2-xy的值
已知:xx-xy=7,xy-yy=4,则xx-yy=( )
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,
x(x+1)-(xx+y)=-3,求(xx+yy)/2-xy的值
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XX+YY=7 XY=-2 X= Y=?
x+y+z=5,xx+yy+zz=6,求xy-xz-yz的解