Answer:
5(x - 5)(x + 4)
Explanation:
Given
5x² - 5x - 100 ← factor out 5 from each term
= 5(x² - x - 20) ← factor the quadratic
Consider the factors of the constant term (- 20) which sum to give the coefficient of the x- term (- 1)
The factors are - 5 and + 4, since
- 5 × 4 = - 20 and - 5 + 4 = - 1, then
x² - x - 20 = (x - 5)(x + 4) and
5x² - 5x - 100 = 5(x - 5)(x + 4)