3x^2-y^2=8 x^2-2xy-3y^2=0 帮忙解两个方程组.x^2+2y=5 x^2+xy+y^2=13

化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] 已知xy/x+y=2,求代数式8x-5xy+8y/-x+3xy-y的值 （-3x^y+2xy)-( )=4x^+xy 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 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 f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? 已知xy/x+y=2,则代数式3x-5y+8y/-x+3xy-y的值 由已知x+y=-2,xy=3那么2(x+xy)-[(xy-3y)-x]-(-xy)等于多少? 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) 当x-y=2xy时,求4x-3xy-4y/xy （12x^2y-8xy^2+16xy）/-3x+2y-4=? (12x^2y-8xy^2+16xy）/-3x+2y-4=? (x^3-2x^2+xy^2)/(x-y)+(x+y)(y-x)=? (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)答案应为-2x-x*x-3x， 已知x,y为正整数,并且xy+x+y=71,x^2y+xy^2=880,求3x²+8xy+3y² x*x-xy=-3,2xy-y*y=-8,求2x*x-4xy+y*y的值 (-x+2y)(2x+y)-(2x+y)(y-2x)-3xy=?因式分解