化简(1) 5xy^2+2x^2y-3xy^2-x^2y ;(2)2(2a^2+9b)+3(-5a^2-4b)

化简：3x^2-[5xy-(x^y-3xy)+4x^2y-8xy] 化简(3x^2-5xy)+{-x^2-[-3xy+2(x^2-xy)+y^2]} 计算：(5-xy/x^3-x^2y)/(1-5/xy)^2*(y-x)^3 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= 5x^2y/-1/2xy*3xy^2 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 计算3xy[2xy-x(y-2)+x-1] 5x^2y-3xy^2+4xy-14xy^2+4xy-2x^2y（化简） 化简!1、（x^2-xy）+xy+y^2 2、3（x^2-xy）-xy+y^2 5xy^2-{2x^y-[3xy^2-（xy^2-2x^2y）]/（-1/2xy）} 化简x^-y^/x^-2xy+y^ 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 化简2x^2y-2xy+3y^2-(5x^2y+3xy-1)的结果是_____. 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