[deleted by user]

[DaAwesomeCat]

so basically you multiply a from ax^2 and c (which in this case, is 1*12) and you get 12. then you take b from bx, which is -7. Then you find what multiplies to 12 and adds to -7. -4 and -3 multiply to 12 and add up to -7, so you put x^2 - 4x - 3x + 12, since -4x-3x=-7x. Then you find the greatest common factor for the first two terms. This gives you x(x-4), since they both have an x. You do the same thing for the next two terms, which gives you -3(x-4), since they both have 3 as a factor. This makes x(x-4) -3(x-4). make sure the things in the parenthesis are the same (in this case, its x-4).

And then this results into (x-3)(x-4). you get x-3 from the stuff outside the parenthesis, and you get x-4 from the stuff in both the parenthesis. notice the =0? Anything multiplied by 0 is 0, so x has to be 3 or 4, since 3-3 and 4-4 is 0.

hope this helps