# Math Help - Find the arithmetic sequence

1. ## Find the arithmetic sequence

Determine an arithmetic sequence knowing the sum Sn if its n first terms is equal to 6n^2 + 7n. For any non zero n

2. ## Re: Find the arithmetic sequence

Start from here: $\frac{n}{2}(2a+(n-1)d)=6n^2+7n$

3. ## Re: Find the arithmetic sequence

When n=1 we get the first term. That is 13. When n=2 we get sum of 1st 2 terms = 38 Hence 2nd term= 25 So common difference = 12

4. ## Re: Find the arithmetic sequence

Originally Posted by biffboy
When n=1 we get the first term. That is 13. When n=2 we get sum of 1st 2 terms = 38 Hence 2nd term= 25 So common difference = 12
That's better than what I said.