Question

A certain arithmetic sequence has the following explicit formula for the nth term: an = 3 + (n - 1)(8) The same sequence has the following recursive formula: an = an-1 + _____ What number belongs in the blank space in the recursive formula? A. 5 B. 3 C. 8 D. 24

Answer 1

From the explicit formula:
an=3+(n-1)8
simplifying this we get:
an=3+8n-8
an=8n-5
thus 
the recursive formula is:
an=an-1+
the missing part is the common difference which is 8