Final answer:
Yes, you can write a recursive formula for an arithmetic sequence given the fifth term and the common difference. Geometric sequences are related to exponential functions. The reliability of the researcher's method of predicting the populations for years 6, 10, and 50 is uncertain without more information.
Step-by-step explanation:
In an arithmetic sequence, the recursive formula is given by an = an-1 + d, where an is the nth term, an-1 is the (n-1)th term, and d is the common difference. So, if you know the fifth term in an arithmetic sequence and the common difference, you can write a recursive formula for the sequence.
Geometric sequences are related to exponential functions because the terms in a geometric sequence can be expressed as exponential functions, such as an = a1 * r(n-1).
Regarding the researcher's method of predicting the populations for years 6, 10, and 50 using the explicit formula an = 1000 * 2n-1, it would depend on whether the model accurately represents the actual population growth of wombats on Wombat Island. Without more information, it is difficult to determine if the researcher's predictions are reliable.