Answer:
(x - 15)(x + 3)
Explanation:
Consider the factors of the constant term (- 45) which sum to give the coefficient of the x- term (- 12)
The factors are - 15 and + 3, since
- 15 × 3 = - 45 and - 15 + 3 = - 12, hence
x² - 12x - 45 = (x - 15)(x + 3)