00:01
So in this problem, we're being asked to find the sum of this series.
00:04
So let's list out the information we know.
00:07
Well, we know the first term is 2, so a sub 1 is equal to 2.
00:11
We know the last term is 41, so a sub n is equal to 41.
00:17
And to get from one term to the next, we simply keep adding 3.
00:20
Therefore, our common difference is equal to 3.
00:24
So we just need to find n.
00:26
To do this, we can use our formula to find the nth term in an arithmetic sequence, which remember is a sub n equals a sub one plus the quantity of n minus one times d.
00:37
So let's substitute in these values that we know.
00:40
So we're going to have 41 equals 2 plus the quantity of n minus 1 times 3.
00:47
So let's solve for n...