It does some nifty expansions like:
calling a= 5x and b =2
So numbers like 15617 which equal 25^3 - 2^3 can be factored but not always into primes.
15617 = (23)(679)
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.