9-x^2-y^2+4xy,

9-x^2-y^2+4xy 9-x^2-y^2+4xy, (x^2+2xy+y^2-4xy)*(x^2-2xy+y^2+4xy) 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) (x+y)(x+y+2xy)+(xy+1)(xy-1)(x+y)(x-y)+4(y-1) 化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] xy-2{xy-[3x^2y-(4xy^2+0.5xy)]+4x^2y}+6xy^2 （X-3xy+4xy-y）-[-2x-2（xy-3/2xy）-y]+6xy的过程 （-3x^y+2xy)-( )=4x^+xy 已知x^2-xy=4,y^2-xy=9,求代数式x^2-2xy+y^2 已知2x+xy=10,3y+2xy=6.求4x+8xy+9y=? 4x^2y+12xy+9y分解因式 (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)答案应为-2x-x*x-3x， (x^-4y^)/(x^+2xy+y^)/(x+2y)/(2x^+2xy) 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 因式分解3x2+xy-y2+x+9y-43X^2+XY-Y^2+X+9Y-4 解方程组2x*+2xy+4y*+x=19;x*+xy+2y*-y=9 x^3y(-4y)^2+(-7xy)^2*(-xy)-5xy^3*(-3x)^2