Ex: Finding Terms in a Sequence Given a Recursive Formula

This video provides two examples of how to find the terms in a sequence given a(n), which is a recursive sequence formula.

[KnowingMyPc]

To Chenoah and to all those that are wondering how you can get 2 as the answer for "a sub 3". Notice that the "n" in the problem is in the "sub" category. That should immediately tell you that the sum of n-1 will equal a number of the sequence I.e A_1, A_2 etc. Since we are given what sub 1 and 2 are already, you simply add them together. The key is that n is in the sub category.

[Chenoah.]

Thank you for your videos, they help a lot. I must be missing something in this sequence because I am not understanding how a sub 3 is equal to 2. I keep getting 2 when I plug 3 in. It says 1+1 = 2 but I am getting 2+1. I hope that makes sense.

[OveralNoob]

Finally got it, I was struggling with what an+1 and an+2 meant.

[AlphaRaiderWife]

Maybe should have used other terms instead on a_1=1 and a_2=1. I don’t understand if you add these?
Some how some sequences show a_1=2 and a_2=3 and the fourth term is some how 8? I don’t understand how they got this?

[jesseknapp]

I hope you can help. Your examples are on point. however, this formula is addition (a-sub-n -1) The one in my books is a-subn +1 and I can't find even a single video on it.