解
a²-b²-a-b
=(a²-b²)-(a+b)
=(a-b)(a+b)-(a+b)
=(a+b)(a-b-1)
4x²-4x-y²+1
=(4x²-4x+1)-y²
=(2x-1)²-y²
=[(2x-1)-y][(2x-1)+y]
=(2x-y-1)(2x+y-1)
解
a²-b²-a-b
=(a²-b²)-(a+b)
=(a-b)(a+b)-(a+b)
=(a+b)(a-b-1)
4x²-4x-y²+1
=(4x²-4x+1)-y²
=(2x-1)²-y²
=[(2x-1)-y][(2x-1)+y]
=(2x-y-1)(2x+y-1)