Answer:
x² + 9x + 20 = 0
Explanation:
Given a solution x = - a for a quadratic equation then (x + a) is a factor
Here x = - 5 and x = - 4 , then corresponding factors are
(x + 5) and (x + 4)
The quadratic equation is then the product of its factors, that is
(x + 5)(x + 4) = 0 ← expand using FOIL
x² + 9x + 20 = 0