00:01
We're being asked to find the formula to find the nth term in our arithmetic sequence, 5 -1, negative 3, negative 7, negative 11, and so forth.
00:10
Well, remember, our general formula for arithmetic sequences is a -sub -n equals a -11 plus the quantity of n -minus 1 times d.
00:20
So, to write the formula for this particular sequence, we need to know our a -1 value and our d value.
00:27
Well, remember, a sub 1 represents the first term in the sequence, which in this case is 5.
00:34
And d represents our common difference, which is the constant that's getting added to go from one term to the next.
00:40
Well, in this particular case, you might notice that we're adding negative 4 each time.
00:48
So, because we're adding negative 4, that makes d negative 4.
00:53
So now we just need to substitute 5 in for a sub 1 and negative 4 in for d...