Question 16814
1) Factor:
{{{15x^2 - x - 2}}}

What are the factors of 15x^2?
{{{(15x)(x) = 15x^2}}}
{{{(5x)(3x) = 15x^2}}}
{{{(-15x)(-x) = 15x^2}}}
{{{(-5x)(-3x) = 15x^2}}}

What are the factors of -2?
{{{(-1)(2) = -2}}}
{{{(1)(-2) = -2}}}

Now you can use trial & error.  Pick a pair of factors from the first list and a pair of factors from the second list.
But keep in mind that you want the right combination that will make a (-x) for the middle term of your trinomial.

Try: {{{(5x - 1)(3x + 2) = 15x^2 + 10x - 3x - 2}}} = {{{15x^2 + 7x - 2}}} Oops!
Almost...but no cigar!  Try switching the -1 and the 2

{{{(5x + 2)(3x - 1) = 15x^2 - 5x + 6x - 2}}} = {{{15x^2 + x - 2}}} Not quite!
You need a -x not a +x

Try {{{(5x - 2)(3x + 1) = 15x^2 + 5x - 6x - 2}}} = {{{15x^2 - x - 2}}} Bingo!

Now try this approach on your second problem.