SOLUTION: The sum of n term of a series is n^2+2n for all value of n.find the first three terms of the series

Algebra.Com
Question 1188438: The sum of n term of a series is n^2+2n for all value of n.find the first three terms of the series
Answer by mccravyedwin(407)   (Show Source): You can put this solution on YOUR website!
The sum of n term of a series is n^2+2n for all value of n.find the first three terms of the series

The "sum of the first 1 term" is the first term. So substituting n=1 in n2+2n, gives 12+2(1) = 1+2 = 3. 
So the first term is 3.

The sum of the first 2 terms is found by substituting n=2 in n2+2n, which gives 22+2(2) = 4+4 = 8.  Since 
the "sum of the first 1 term" is 3, the second term is 8-3=5.

The sum of the first 3 terms is found by substituting n=3 in n2+2n, which gives 32+2(3) = 9+6 = 15.  Since 
the sum of the first 2 terms is 8, the second term is 15-8=7.

In fact the sequence is the odd numbers beginning with 3,
3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,...
Edwin
RELATED QUESTIONS

The sum of the first n terms of a series is 2n^2−n. Find the nth... (answered by ikleyn)
the sum of the first n terms of a series is 2n^-n find the nth... (answered by Edwin McCravy)
the sum of the first n terms of a series is given by Sn=n^2+2n .Find the rth term and the (answered by ikleyn)
the sum of the first n terms of a series is 5n^2-2n. the r-1 term... (answered by ikleyn)
the sum of the first n terms,Sn of a series is given by Sn=2n*2/(n*n)+1,then is the... (answered by Fombitz)
If the sum of n terms of a series is 2n^2+3n+4. Find the series and also its nth... (answered by ValorousDawn)
The Question: "The nth term of a series is {{{ (1/2)(2n-1) }}}. Write down the (n+1)th (answered by stanbon)
Sn is the sum of the first n terms of a series given by Sn=n^2-1. Find the nth... (answered by greenestamps)
Find the sum of the first 10 terms of the series defined by the formula: a(n) = -2n +... (answered by jim_thompson5910)