x³-y³-x²y+xy²
=(x³-x²y)+(xy²-y³)
=x²(x-y)+y²(x-y)
=(x-y)(x²+y²)
2a²-b²+ab-2a+b
=(2a²+ab-b²)-(2a-b)
=(2a-b)(a+b)-(2a-b)
=(2a-b)(a+b-1)