解
x²-x-4y²+2y
=(x²-4y²)-(x-2y)
=(x-2y)(x+2y)-(x-2y)
=(x-2y)(x+2y-1)
4a²b-3ab²-a³
=-a(a²-4ab+3b²)
=-a(a-3b)(a-b)