(x²+x-6)(x²+x-8)-24
=(x²+x-6)[(x²+x-6)-2]-24
=(x²+x-6)²-2(x²+x-6)-24
=[(x²+x-6)-6][(x²+x-6)+4]
=(x²+x-12)(x²+x-2)
=(x-3)(x+4)(x-1)(x+2)
(x+1)(x-2)(x-3)(x-6)+20
=[(x+1)(x-6)][(x-2)(x-3)]+20
=(x²-5x-6)(x²-5x+6)+20
=(x²-5x)²-36+20
=(x²-5x)²-16
=(x²-5x+4)(x²-5x-4)
=(x-1)(x-4)(x²-5x-4) (有理数范围内到此为止)
=(x-1)(x-4)[x-(5+√41)/2][x-(5-√41)/2] (实数范围内)