How do you write a recursive formula for a sequence whose first three terms are 1, 1 and 3? I feel like the question didn't give enough numbers.

Question

anonymous · Answer

hey hottie

ybarrap · Answer

This is one pattern that I can think of, which might work

1 +1 =2
1+2=3
3+3=9
9+4=12
12+5=17
...

ganeshie8 · Answer

infinite patterns are possible as there is not sufficient info. another pattern is :-

$\large a_1 = 1$
$\large a_{n+1} = 3^{n-1}$

ybarrap · Answer

yes, that's true also

hkmiu · Answer

@ybarrap that was what I was thinking too. But there wasn't any 2's in the pattern. If there was it bould be a fibonacci sequence. idk. 
@ganeshie8, for the formula, for a2 I got 3. But 3 was supposed to be a3.. It's a bit confusing.

ganeshie8 · Answer

$\large a_1 = 1$

$\large a_2 = a_{1+1} = 3^{1-1} = 3^0 = 1$

$\large a_3 = a_{2+1} = 3^{2-1} = 3^1 = 3$

hkmiu · Answer

That made sense when you explained it! Thanks again! @ganeshie8

ganeshie8 · Answer

np :) but you're right, there is not sufficient data here, if we think a bit we can form many  recursive formulas like above

ganeshie8 · Answer

another one :-

$\large a_1 = 1$
$\large a_{n+1} = 2^n-1$

hkmiu · Answer

Aaaaaaah, :(. I don't like recursion and special sequences! I've been stuck on this lesson for a good 3 hours now.

hkmiu · Answer

I submitted my work & got a 90. It gave me the possible answer ----> http://media.education2020.com/evresources//423123.jpg It doesn't look the same to me but I got it right. (or maybe my eyes and brain are just too tired to realize)...

ganeshie8 · Answer

congrats ! :) yes that works too...