x^2+y^2=20 x^2-3xy+2y^2=0

（-3x^y+2xy)-( )=4x^+xy x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? 若1/x-1/y=2,求3x-2xy-3y/x-xy-y的值3x-2xy-3y/x-xy-y 不好意思，是3x-2xy-3y/x-2xy-y x^2+xy+x=36,y^2+xy+y=20,求x+y. f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? 由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少? 当x-y=2xy时,求4x-3xy-4y/xy 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) (x^3-2x^2+xy^2)/(x-y)+(x+y)(y-x)=? (-x+2y)(2x+y)-(2x+y)(y-2x)-3xy=?因式分解 已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理.已知X+Y=3XY,求2X+2Y-XY除以X+Y+2XY的值,要算理. x+y=-3 xy+x+y=-2 x/y+y/x=? x-y/xy=( )/x^3y^2 (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)答案应为-2x-x*x-3x， （x+2y-3xy)-(-2x-y+xy),其中x+y=1/2,xy=-1/2 已知x+xy+y=3,则(3x+2xy+3y)/(2x+xy+2y)= 已知x-y=3xy,则2x+3xy-2y除以x-2xy-y=? 已知x-y=3xy,则2x+3xy-2y/x-2xy-y=