http://postimg.org/image/lh7ga876t/ [Broken] Hi, I have a basic question concerning definition of the word 'factorization'. Does Spivak consider factorization as development of factors ? He goes from saying the "factorization" x2−3x+2=(x−1)(x−2) is really a triple use of P9 and goes on showing development. P9 says : If a,b, and c are any numbers, then : a⋅(b+c)=a⋅b+a⋅c Also, when Spivak does the following : (x−1)(x−2)=x(x−2)+(−1)(x−2) does he use any property or just assumes it as like this ? I know whats happening, just curious if there's any justification to it. Thank you !