Jeremy can determine the total number of miles walked at a constant speed by using the formula an=an-1+3. if a1=2, what are the first three terms of the sequence?
a. 1, 5, 8
b. 2, 6, 18
c. 2.-1, -4
d. 2, 4, 6

I believe that the answer to this question is not found in the choices. The first term a1 = 2. The common difference is 3. 
Since you are already given the first term, you simply just add 3 to find the second term, and add 3 again to find the third term of the sequence.

So the answer must be 2, 5, 8.