Answer:
a² + 81 is your answer
Step-by-step explanation:
First, expand the power:
(a - 9)² = (a - 9)(a - 9)
Use the FOIL method.
(a)(a) = a²
(a)(-9) = -9a
(-9)(a) = -9a
(-9)(-9) = 81
Combine like terms: a² - 9a - 9a + 81
a² (- 9a - 9a) + 81
a² - 18a + 81
Simplify. Combine like terms:
18a + a² - 18a + 81
a² + (18a - 18a) + 81
a² + 81
a² + 81 is your answer
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