Factor the polynomial completely y^3+6y^2-4y-24

You might try factoring by grouping first.

Note that y^3+6y^2 = y^2 (y+6), and that - 4y-24 = - 4 (y+6). So, (y+6) is a factor common to the first group of 2 terms and the 2nd grp of 2 terms.

We get (y+6) [y^2 - 4]. Note that y^2-4 is easily factorable: (y-2) (y+2),

so we now have three factors of the original poly:

(y+6), (y-2) and (y+2) (answer)

y3-6y2-4y+24 Final result : (y + 2) • (y - 2) • (y - 6)