How do you factor 15b2 - 7b - 2?

Answer 1

(5b+1)(3b-2)

You know that 15 only has four factors: 1,3,5, and 15. So the first numbers in the parenthesis are either going to be 1 and 15, or 3 and 5. I would try 3 and 5 first because they are closer together, and the other coefficients in the problem are not super large. So I had (5b )(3b ). Then, I looked at -2. There are two ways to get that: -2 x 1 or -1 x 2. Put one set into the parenthesis, foil it out and see if its right. If not, try the other. That's it!