xy=9,x-y=-3,则xx+3xy+yy等于多少

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 x(x+1)-(xx+y)=-3,求(xx+yy)/2-xy的值 3xx+xy+yy=15 已知x=1/2 y=1/3 z=1/4 则(xx+yy-zz+2xy)/(xx-yy+zz-2xz) 得多少? 知x/3=y/4=z/5,求(xy+yz+xz)/xx+yy+zz 若x/3=y/4=z/5,则(xy+yz=xz)/(xx+yy+zz)的值为 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xx+xy=1,xy-yy=-4,则xx+2xy-yy= X-Y=4,xy=12则xx+YY的值 已知(x+y)(x+y)=25,(x-y)(x-y)=9求xy与xx+yy的值 由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少?