x2-2xy-2y2 在实数范围内分解因式 两种答案

方程x^2-2x-2=0的根是
x=1±√3
所以x^2-2xy-2y^2
=(x-y-√3y)(x-y+√3y)

方程2y^2+2y-1=0的根是
y=(-1±√3)/2
所以x^2-2xy-2y^2
=-(1/2)(2y+x-√3x)(2y+x+√3x)

原式=x2-2xy+y2-3y2=(x-y)2-3y2=(x-y-根号3*y)(x-y+根号3*y)

1,x2-2xy-2y2 =（x-y)^2-y^2=(x-2y)x
2,x2-2xy-2y2= =x^2-2xy+y^2-3y^2=(x-y)^2-3y^2=(x-y-根下3y)(x-y+根下3y)