Math Counts 6

Algebra Level 2

The Fibonacci sequence is defined by the function F(n) = F(n-2) + F(n-1), for n>2 and F(1)=F(2)=1. What is the value of F(11)?

1 solution

Henry U
Oct 31, 2018

Using the given definition we get the following values

$F(1) = 1$

$F(2) = 1$

$F(3) = F(2) + F(1) = 2$

$F(4) = F(3) + F(2) = 3$

$F(5) = F(4) + F(3) = 5$

$...$

$F(9) = F(8) + F(7) = 34$

$F(10) = F(9) + F(8) = 55$

$F(11) = F(10) + F(9) = \boxed{89}$