Question

How do you find the first five terms given `a_1=-1`, `a_2=5`, `a_(n+1)=a_n+a_(n-1)`?

Answer 1

First five terms are `{-1,5,4,9,13}`

Explanation:

As `a_(n+1)=a_n+a_(n-1)`, we have

`a_3=a_(2+1)=a_2+a_(2-1)=a_2+a_1=5-1=4`

`a_4=a_(3+1)=a_3+a_(3-1)=a_3+a_2=4+5=9`

`a_5=a_(4+1)=a_4+a_(4-1)=a_4+a_3=9+4=13`

Hence, first five terms are `{-1,5,4,9,13}`