The Fibonacci sequence is F (n) = F (n - 1) + F (n - 2).

If F (6) = 8 and F (7) = 13, which of the following is true?

A. F (8) = 19 B. F (13) = 21 C. F (8) = 21 D. F (5) = 3

C. F (8) = 21

Step-by-step explanation:

Given F (n) = F (n-1) + F (n-2), F (6) = 8 and F (7) = 13.

F (8) = F (7) + F (6) = 13 + 8 = 21

F (13) is way larger than 21, so answer B is wrong.

F (5) = 3 - if you went back, you'd get F (7) = F (6) + F (5), so F (5) = F (7) - F (6) = 13 - 8 = 5, which means D is also wrong.

C. F (8) = 21

Given F (n) = F (n-1) + F (n-2), F (6) = 8 and F (7) = 13.

F (8) = F (7) + F (6) = 13 + 8 = 21

F (13) is way larger than 21, so answer B is wrong.

F (5) = 3 - if you went back, you'd get F (7) = F (6) + F (5), so F (5) = F (7) - F (6) = 13 - 8 = 5, which means D is also wrong.