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Numerade Educator



Problem 12 Easy Difficulty

List the first five terms of the sequence.
$ a_1 = 2, a_2 = 1, a_{a+1} = a_n - a_{n-1} $


$\begin{aligned} a_{1} &=2 \\ a_{2} &=1 \\ a_{3} &=-1 \\ a_{4} &=-2 \\ a_{5} &=-1 \end{aligned}$


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Video Transcript

Okay, This is supposed to be in plus one equals a n minus a and minus one. And the first terms, the first two terms in the sequence or given to us, we have a one is two. It too is one a three. We have to reference this recursive relation. So a three is acting as their hay and plus one, which means that our A N is acting as our eight two. This is in our and minus one is like the A one that we have here. Okay, so a three is a two minus a one. So one minus two, minus one and then the same thing for a four. A four is now going to be a three minus eight two. So a three is minus one. A two is minus one. So this gives us minus two in a five is a four minus. Hey, three a four is minus two and then a three is minus one. So minus minus one will make us be having one. This puts us at minus one. The first five terms are sequence