An arithmetic progression is defined by the general term an=12−2n.
(a) Write the first five terms of this progression.
(b) Decide whether this progression is finite or infinite. Give a clear reason for your answer.
(c) Suppose the progression is modified so that it stops just before the terms become negative. How many terms will now be included? Explain your reasoning.
(d) In general, using an=a+(n−1)d, state in one sentence the condition on n that makes any AP finite.