00:01
So in this problem, what we're being asked to do is to find the sum of the first 70 positive integers.
00:05
Well, let's first write out the first 70 positive and, if i remember correctly, i think i missed this, even integers.
00:16
So this should be even integers because that will play a role.
00:19
Okay, well, what would our first even integer be? well, that would be two, followed by four, six, eight, ten, etc.
00:28
Well, notice that this now is an arithmetic sequence.
00:32
To get from one, term to the next, we add a constant.
00:34
So essentially, we're trying to find the sum of an arithmetic sequence.
00:38
Well, we have a formula to do this.
00:39
It says that s of n is equal to n over two times the quantity of two times a sub one plus d times n minus one.
00:48
So the first thing we need to know is n.
00:50
Well, n would be the number of terms in the sequence...