Question 87408
I use a trial and error method which I explained in detail on my website.

{{{6x^2-xy-5y^2}}} 
{{{(6x +5y)(x-y)}}}


{{{25x^2-20xy+4y^2}}}

{{{(5x-2y)(5x-2y)}}}
{{{(5x-2y)^2}}}


If anyone needs more explanation on this type of factor (or on any type of factoring for that matter), see my website by clicking on my tutor name "rapaljer" anywhere in algebra.com, then look for "Basic Algebra", then "Samples from Basic Algebra: One Step at a Time", "Chapter 2", "Advanced Trinomial Factoring."  For other types of factoring, send me an Email and I will send you a link from my website that should be helpful.  Some of the explanations are in LIVING COLOR.


R^2  Retired from SCC