text: how do you factor out? x^3-4x+3x^2-12=0 rearrange them to x^3 + 3x^2 -4x -12 = 0  then group the first 2 and the second 2  (x^3+3x^2) + (-4x - 12) = 0  from the first group, you can pull out x^2; from the second group, you can pull out -4  x^2*(x+3) -4*(x+3) = 0  now you can pull out (x+3)  (x+3)(x^2-4) = 0 --- now x^2 - 4 is a difference of squares, which are factored a^2-b^2=(a+b)(a-b) so you can factor x^2-4 even further  (x+3)(x+4)(x-4)=0