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April 30th, 2014, 07:05 PM  #1 
Newbie Joined: Apr 2014 From: Denver, Colorado Posts: 1 Thanks: 0  Arithmetic and geometric sequence problems Algebra 2
If anybody would be able to help me with either of the following problems that would be great (I don't know how to do a subscript so I'm just going to write "sub"): Given the explicit formula for an arithmetic sequence find first 5 terms and 34th term: a sub n = 11 + 7n If the first term of a geometric sequence is 2 and the common ratio r is 6, find the next 3 terms in the sequence and write the recursive formula. (For this one I already have the first part and just need the recursive formula) 
May 1st, 2014, 12:21 AM  #2  
Member Joined: Jan 2014 From: Tashkent, Uzbekistan Posts: 52 Thanks: 2  Quote:
Quote:
So, by rewriting the common formula we get $\displaystyle a_n=a_1d+dn$. Now we have $\displaystyle \begin{eqnarray} a_1d&=&11 \\ dn & = & 7n \end{eqnarray}$ Try to complete it yourself  
May 1st, 2014, 01:19 AM  #3 
Senior Member Joined: Apr 2014 From: Europa Posts: 584 Thanks: 177  $\displaystyle \dfrac{..}{..}\ \ a_1 = 2,\ r=6\\\;\\ \qquad a_n = a_1\cdot r^{n1}\\\;\\ \qquad a_n= 2\cdot 6^{n1}$
Last edited by aurel5; May 1st, 2014 at 01:25 AM. 

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