Factor2[poly] factors a polynomial in a standard
way.
Factor2 works sometimes better than Factor on
polynomials involving rationals with sums in the denominator.
Factor2 uses Factor internally and is in
general slower than Factor. There are four possible
settings of the option Method
(0,1,2,3). In
general, Factor will work faster than
Factor2.
(a - x) (b - x)
{Factor2[%], Factor[%]}(a-x) (b-x)
\{(a-x) (b-x),-((a-x) (x-b))\}
ex = Expand[(a - b) (a + b)]a^2-b^2
Factor[ex](a-b) (a+b)
Factor2[ex]a^2-b^2
Factor2[ex, FactorFull -> True](a-b) (a+b)