x^2+6xy+9y^2+3x+9y-4=0为什么将它因式分解后,就可以看成是2条直线的方程啊

化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)答案应为-2x-x*x-3x， 4x-y/2根号x+根号y 9x-6根号xy+y/3根号x-根号y 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 已知x^2+9y^2-2x-6y+2=0,求{-（xy/（x-y）^2}^4*(y^2-xy/x)^3*x^4/y^10/(x/xy-y^2)^5的值 (2x+3y)(2x-3y)(4x^2+6xy+9y^2)(4x^2-6xy+9y^2) (9x^2y-6xy^2)/3xy (X-9y)/(6xy^2-(x+3y)/(9x^2y) 2x-3y/xy×2x^2y^2/6x-9y 求x^3 - 6x^2y + 11xy^2 - 6y^3 思路x^3 - 6x^2y + 11xy^2 - 6y^3= x^3 - 3x^2y + 2xy^2 - 3x^2y + 9xy^2 - 6y^3= (x^2 - 3xy + 2y^2)(x - 3y)= (x^2 - 2xy - xy + 2y^2)(x - 3y)(x - y)(x - 2y)(x - 3y)求思路 3x*x+5xy-2y*y+x+9y-4 3x*x+5xy-2y*y+x+9y-4请因式分解 因式分解:12xy^2(y-x)+xy^3(x-y)+4x^2y(x-y) 9x^2y+y^3-6xy^2因式分解 因式分解6xy^2-9x^2y-y^3 6xy^2-9x^2y-y^3因式分解 x^2y-6xy^2+9y^3 6xy-9x^2y-y^3 因式分解