(x+y)²+4(x+y)-5
=（x+y+5)(x+y-1)
(2a+b)²-4(2a+b)+3
=(2a+b-3)(2a+b-1)
6y²-11xy-10x²
=(2y-5x)(3y+2x)
ax²-a³-2ax——2a²
=a(x²-a²)-2a(x+a)
=a(x+a)(x-a)-2a(x+a)
=a(x+a)(x-a-2)