# Thread: Intermediate Algebra - Factoring

1. ## Intermediate Algebra - Factoring

Why does that (m-n) suddenly disappear?? below pic.

Thank you!

2. Say you have:

$\displaystyle a=(m-n)$, $\displaystyle b=(m^2+mn+n^2)$, and $\displaystyle c=(m+n)$

Then,

$\displaystyle ab+ca$

taking out the common factor of $\displaystyle a$ you have:

$\displaystyle a(b+c)$

3. Ah, I think I understand now. Thank you very much : )