Lowest form of x4+x3y+x2y2x3−y3
x3(x−y)
x2(x+y)
x2(x−y)
x2+y(x+y2)
x4+x3y+x2y2x3−y3 = x2(x2+xy+y2)(x−y)(x2+xy+y2) = x2(x−y)