Question

The recursive equation of a sequence is given by a Subscript n Baseline equals a Subscript n minus 1 Baseline plus 7 for n is greater than or equal to 1.



If a Subscript 5 Baseline equals 43, what is a Subscript 1 Baseline?

Answer options with 5 options
A.
1

B.
6

C.
8

D.
10

E.
15

Answer 1

The recurrence adds 7 each step, so a5 = a1 + 4·7 = a1 + 28. Thus a1 = 43 − 28 = 15.

Answer: E.