Answer:
(x +5) (x +4) = 0
Step-by-step explanation:
x^2 + 9x +20 = 0
x^2 + 4x + 5x +20 = 0
x(x + 4) + 5(x + 4) = 0
see below
x^2 + 9x = -20
x^2 + 9x + 20 = 0
factor the expression
(x + a)(x + b)
a + b = 9
a = 4
b = 5
ab = 20
rewrite the factor expression:
(x + 4) (x + 5)
x + 4 = 0 and x + 5 = 0
therefore,
x = -4
x = -5
