Mark M. answered 06/10/23
Retired math prof. Calc 1, 2 and AP Calculus tutoring experience.
9n / (6n + 5) = 9 / (6 + 5/n)
(b). As n goes to infinity, 9 / (6 + 5/n) approaches 9/6 = 3/2. So the sequence converges to 3/2.
(a). Since the terms of the series do not approach 0, then by the nth term test for divergence, the series diverges.