x^2-ax-a-1

问题描述:

x^2-ax-a-1

x^2-ax-a-1
=(x²-1)-(ax+a)
=(x+1)(x-1)-a(x+1)
=(x+1)(x-1-a)
=[x-(a+1) ](x+1)
即x^2-ax-a-1