CAPE Pure Mathematics Unit 2 · May/June 2016 · Paper 1 · Question Q19

For the recurrence relation a_{n+1} = a_n - a_{n-1} where a_1 = 1 and a_2 = 3, the value of a_5 is

1. (A)-3
2. (B)-1
3. (C)1
4. (D)3