Answer:
domain { a ∈ R , a ≠ - 5 }
Explanation:
the denominator of f(a) cannot equal zero as this would make f(a) undefined. Equating the denominator to zero and solving gives the value that a cannot be.
a + 5 = 0 ( subtract 5 from both sides )
a = - 5 ← excluded value
domain { a ∈ R, a ≠ - 5 }