I'm trying to figure out the equivalent expression to 3x^2 + 6x – 24.

Question

I came down to these two choices: 3(x + 2)(x – 4) and 3(x-2)(x+4). I am wondering what makes the difference, and which one is correct. Please, step by step solving, so I can understand

Answer 1

3x^2+6x-24

factor out a 3

3(x^2+2x-8)

4*(-2)=-8 and 4+(-2)=2, the coefficient of 2x

3(x+4)(x-2) is correct but 3(x+2)(x-4)=3(x^2-2x-8)=3x^2-6x-24 is incorrect because you get -6x and not +6x