The formula a(n) = 2 - 5(n-1) is in the form a(n) = a1 + d(n-1)
where a1 = first term = 2 d = -5 = common difference
The first term is carried over to the recursive formula. We start with a1 = 2. The next term after that is found by subtracting 5 from the previous term. So second term = (first term) - 5 third term = (second term) - 5 and so on
