Answer:
(a + 3)
Step-by-step explanation:
a³ - 9a = a(a² - 9) = a(a + 3)(a - 3)
a² + a - 6 = (a - 2)(a + 3)
a⁴ + 27a = a(a³ + 27) = a(a - 3)(a² + 6a + 9) = a(a - 3)(a + 3)(a + 3)
HCF = (a + 3)
Hope it helps.
;)
<3
