Multiply the first and last number together (5 × -15 = -75). Find factors of -75 that add to -22 (-25 + 3 = -22). Expand the middle term using these numbers.
5x^2 - 25x + 3x - 15 = 0
Factor the equation in two groups. You can pull 5x out of 5x^2 - 25x. You can pull 3 out of 3x - 15. In both parts, you should be left with x - 5. Proceed to write the factors of the two groups and the result as a binomial.
