若x+y=9,xy=20则 x^2+y^2=_____, (x-y)^2=_____

若x+y=9,xy=20则 x^2+y^2=_____, (x-y)^2=_____ 已知x-xy=20,xy-y=-10,则x-y=( ),x+y-2xy=( ). 已知x-xy=20,xy-y=12,则x-y= ,-2xy+x+y= 已知x-xy=20 xy-y=12,则x-y=（ ）,x+y-2xy=（ ）. 已知:x-xy=20,xy-y=12,则x-y=...,-2xy+x+y=... 已知x-xy=20,xy-y=-10,则x-y=?,x+y-2xy? 若x+y分之xy=2,则-x+3xy-y分之3x-xy+3y=多少? 若xy/x+y=2,则3x-5xy+3y/-x+3xy-y=?/是分之 若x+y分之xy=2,则-x+3xy-y分之3x-xy+3y=多少? 若xy/x+y=2,则3x-xy+3y/-x+3xy-y= 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? |x|/x+y/|y|+xy/|xy|= 若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=? 若x.y>0,9x+y=xy,则x+y的最小值为? 若x.y>0,9x+y=xy,则x+y的最小值为? 若实数x,y满足x^2-xy-y^2 =0,则x/y=? 若正实数x.y满足x+y=xy,则x+2y的最小值