an = an−1 + 3an−2, a0 = 1, a1 = 2

Question

zehanz · Answer

What do you have to do with this sequence?

zehanz · Answer

Maybe it's clearer to write it as: $$a_n=a_{n-1}+3a_{n-2}$$$$a_0=1,a_1=2$$

anonymous · Answer

its a recursive sequence

anonymous · Answer

Yeah sorry

anonymous · Answer

im trying to figure it out because the way i keep solving it is apparently wrong by the book

zehanz · Answer

Yes, I see that, but what is your question about it?
Do you need terms of this sequence?

anonymous · Answer

yes how do you solve it

zehanz · Answer

It says: 
If you want to know a certain number of this sequence, you need the two numbers before it.
Take the last number and add 3 times the number before it to get the new one.

That is why there are two start numbers given.$$a_2=a_1+3a_0$$$$a_3=a_2+3a_1$$So you can calculate every number in the sequence.

I don't understand what you mean by solve it.

anonymous · Answer

Okay so if i was to do it like that then .. a2 = 2 + 3(1) = 5
right?

zehanz · Answer

OK

anonymous · Answer

and a3 = 5 + 2 = 7

anonymous · Answer

is that right or wrong because my book says im wrong

zehanz · Answer

You are, because it is 5 + 3*2 = 11

anonymous · Answer

ohh true

anonymous · Answer

sorry about that last part but the book says

anonymous · Answer

dont worry i see the mistake

anonymous · Answer

lol i never took into consideration a0 and a1 as being apart of the answer so i was so confused as to how they got 1,2,5, then 11 lol

zehanz · Answer

So 
a4 = 11 + 3*5 = 26
a5= 26 + 3*11 = 59 etc.

anonymous · Answer

thank you 
lol

zehanz · Answer

YW!

a0 and a1 are needed to give you a way to "start up"..

anonymous · Answer

yea