x^3+9x^2+26x+24
= x^3 + 2x^2 + 7x^2 + 14x + 12x + 24
= x^2 (x+2) + 7x (x+2) + 12 (x+2)
= (x^2 + 7x + 12)(x+2)
= (x+2)(x+3)(x+4).