Question 94592
15x2 - 7x -2
  [split the middle or "c" term into two terms]
. 
Technique for finding the middle or "c" term:
Factor 15x^2: (3x)(5x)
Factor 2: (-2)(1)
Look for combinations amongst the factors that will add up to (-7)
The combination will be (5x)(-2)+(3x)(1)= -10x+3x=-7x
.
Re-write the expression:
15x^2-10x+3x-2
.

15x^2-10x+3x-2  [factoring using the grouping method]
15x^2+3x-10x-2 [obtained through trial-and-error]
3x(5x+1)-2x(5x+1)
(3x-2x)(5x+1)