(x-1)(x+2)(x-3)(x+4)+24=(x²+x-2)(x²+x-12)+24=(x²+x)²-14(x²+x)+24+24=(x²+x)²-14(x²+x)+48=(x²+x-6)(x²+x-8)=(x+3)(x-2)(x²+x-8)
