We want to factor 3a² - 5ab - 2b².
Note that
(3a)*(-2b) + a*b = -6ab + ab = -5ab
(3a)*a = 3a²
b*(-2b) = -2b²
Therefore
3a² - 5ab - 2b² = (3a + b)(a - 2b)
The factors are (3a + b) and (a - 2b).
Answer:
One of the factors is (3a + b).
Another factor is (a - 2b).