Ok so basically, when you say multiply A by C, that is simplifying.
And in this case, you are factorising in this question. You turn back into brackets basically.
We have: 72x^2 - 32
x^2 = x squared
factorising means finding the factor of.
(Forget the x squared for the moment to make life easier)
Factors of 72: 1 and 72 2 and 36 3 and 24 4 and 18 6 and 12 8 and 9 (9 and 8 = it repeats so we stop there)
And then factors of 32: 1 and 32 2 and 16 4 and 8 (8 and 4 = repeats so we stop there)
Notice how we see 8 twice in both factors of 72 and 32, this means that we use 8 as the main number we are going to multiply each of the 2 numbers in the brackets by. This is because it is the biggest common factor - this is what we have!
This is what we would have: 8(9-4)
BUT, that is not the answer! Keep in mind we have the x squared too
But, 32 doesn’t have it?!!
It would be: 8(9x^2 - 4)
Do you get it??
Try to simplify it! Does it equal to 72x^2 - 32?
(And I am so very sorry for the long explanation, once you get the hang of it, it makes sense. Hope my explanation helped) :)
