Question 568309
{{{12b^4+36b^3-20b^2}}}
the first step is to see if there is something we can factor out from each term. 

If I rewrite everything like this, its more clear 
{{{12*b*b*b*b+36*b*b*b-20*b*b}}}
or if I do a prime factorization of each number like this:
{{{3*2*2*b*b*b*b+3*3*2*2*b*b*b-2*2*5*b*b}}}

So each term has 2*2*b*b which is 4b^2

so I need to factor out 4b^2 from each term
4b^2*(3b^2+9b-5)
and we can factor further if need be but you can probably stop here.

*[invoke quadratic "x", 3, 9, -5 ]