First times First has to come out to . This would have to be 2x*x
The Last times Last has to come out to +1. This would have to be 1*1, with the SAME signs--that is either a (-1)*(-1) or a (+1)*(+1).
Now, the middle term must come out to a -3x, so the signs must both be negative.
The Lesson on Advanced Trinomial Factoring can be found in algebra.com or go to my own website by clicking on my tutor name "rapaljer" anywhere in algebra.com. Next, click on "Basic Algebra", then "Samples from Basic Algebra: One Step at a Time", then in Chapter 2, look for the section about "Advanced Trinomial Factoring." While you are there, check out ALL the sections on Factoring. There are several sections devoted to this important skill.