Respuesta :

Answer:

a² - 5a - 36

Step-by-step explanation:

(a - 9)(a + 4)

each term in the second factor is multiplied by each term in the first factor, that is

a(a + 4) - 9(a + 4) ← distribute parenthesis

= a² + 4a - 9a - 36 ← collect like terms

= a² - 5a - 36

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