7x^2+3y+xy+21x
1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y)
x^3y(-4y)^2+(-7xy)^2*(-xy)-5xy^3*(-3x)^2
xy=-2,x+y=3,求代数式(4xy+12y)+[7x-(3xy+4y-x)]
(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)
已知x=3y,试求(x-y)^2+2xy-y^2/x^2+7xy+y^2
因式分解:8(x-2y)-x(7x+y)+xy.
计算(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-x^y^7+y^8)(x^2+xy+y^2)
x^8-x^7y+x^6y^2-x^5y^3+x^4y^4-x^3y^5+x^2y^-xy^7+y^8
已知xy^2=-2求xy(2x^3y^7+5x^2y
计算3xy[2xy-x(y-2)+x-1]
计算:3xy[2xy-x(y-2)+x]
xy/3x+2y=1/8 xy/2x+3y=1/7