求证3x^2-8xy+9y^2-4x+6y+13>0
(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)
化简:x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y)
x^8-x^7y+x^6y^2-x^5y^3+x^4y^4-x^3y^5+x^2y^-xy^7+y^8
若x>0,y>0,x+y>2,求证:1+xy
x*-2xy+3y*=9 4x*-5xy+6y*=30
已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}
因式分解:3x^2y+6xy-4x-8
因式分解 3x^2-6xy-4x+8y
2 21.(2x+3y) -(x+2y) 2 2 2 22.3|x-3|+x -6xy+9y =0 则x y+2xy=?
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)
1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y)
x+y=8,xy=-2,求(5xy+4x+7y)+(6x-3xy)-(4xy-3y)的值