①-1/3（9x^2-3)+6(2/3x^2+1)②x^2y-(6xy+3x^2y-xy^2)+（5xy+2x^2y)过

(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y) 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) 计算3xy[2xy-x(y-2)+x-1] x^2-xy-6y^2+3xy+y+2 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= xy(xy+1)+(xy+3)-2(x+y+2分之一）-(x+y-1)的平方 (-3分之1xy)的平方×[xy(2x-y)-2x(xy-y的平方)] [3xy(1-x)-6xy(x-1/2)]*2x*(-xy)平方,x=-1 y=2 ； 3xy平方（-1/3x平方y+4 计算：(5-xy/x^3-x^2y)/(1-5/xy)^2*(y-x)^3 5x^2y/-1/2xy*3xy^2 (1)已知x+y=6,xy=-3,x^2y+xy^2=