Find the next two terms in the sequence –5, 8, –13, 20, –29, …. Write a formula for the nth term. Identify the formula as explicit or recursive. Please explain your answer.

Question

Find the next two terms in the sequence –5, 8, –13, 20, –29, …. Write a formula for the nth term. Identify the formula as explicit or recursive.  Please explain your answer.

anonymous · Answer

These are the answer choices.
A.
40, –53; an = (–1)n • (an – 1 + 2n – 1); explicit
 
 B.	
 
39, –50; an = (–1)n • (an – 1 + 2n – 1); explicit
 
 C.	
 
40, –53; an = (–1)n • (n2 + 4); recursive
 
 D.	
 
none of these

jim_thompson5910 · Answer

hint: something like  a_(n-1) on the right side means you're dealing with a recursive equation

anonymous · Answer

Right, and those say they are explicit, so they are not correct?

anonymous · Answer

I know the formula on C. works,  but it is not a recursive formula, so is it none of these then?

jim_thompson5910 · Answer

that is correct, A and B are false

jim_thompson5910 · Answer

C works, but yeah I just noticed that too, it should be explicit

anonymous · Answer

@jim_thompson5910  Hey, thanks for the medal, you get one too! Thank you for your help!  I hope I can call on you again in the future!

jim_thompson5910 · Answer

you're welcome