Given the sequence $7, 11, 15, 19, …$.

1. What kind of sequence is it?

   Hint (a):

   How do you get from one term to the next?
   By adding or by multiplying?

2. Write an explicit equation for the sequence.

   Hint (b):

   See the online help for problem 5-68. Remember that $t(n) = mn + t(0)$.

3. Is $109$ a term of the sequence? If so, which term is it?

   Hint (c):

   Let $t(n) = 109$ in the equation you wrote for part (b).
   Solve for $n$. Remember that n is the term number.

   Answer (c):

   $n = 26.5$, so no, $109$ is not a term in the sequence.