x,+y=5 xy=3 求xx+yy

x,+y=5 xy=3 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-2xy 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 知x/3=y/4=z/5,求(xy+yz+xz)/xx+yy+zz x-y=3,(x+y)(x+y)=25,求xy/xx+yy的值? x+y+z=5,xx+yy+zz=6,求xy-xz-yz的解越快越好 若xx+yy-2x-6y+10=0,求分式（xx-yy）/xy的值. 已知XX—XY=5,XY—YY=-3,求代数式XX—YY和XX—2XY+YY 已知xx+yy=7,xy=-2,求多项式5xx-3xy-4yy-11xy-7xx+2yy的值. xx+2xy+yy=1 xx-2xy+yy=49 求xx+yy,xy. 已知xx+yy+4x-6y+13=0,求（xx-2x）/xx+3yy的值. xy=9,x-y=-3,则xx+3xy+yy等于多少 已知x-y=5,y-z=4,求xx+yy+zz-xy-yz-xz的值 (x+2y+2m)(2x-y+n)=2xx+3xy-2yy+5y-2,求m,n的值 已知x+y=7,xy=-8,求xx+yy 若x-y=4,求(xx+yy)÷2-xy的值