Hello from MrBillDoesMath!
Answer: q= 8 and q = -1 are not in the domain of the function
Discussion :
In this problem, the domain restrictions are where the denominator
( q^2- 7q -8) equals 0. Factor the denominator:
q^2 - 7q - 8 = (q-8)(q+1)
so the values q = 8 and q = -1 are NOT in the domain.
Regards, MrB