00:01
Hi, in this question we are asked to give a recursive definition for this formula, for this function f, when we define f of n to be the sum of first n positive integer.
00:15
So it's going to be 1 plus 2 plus 3 and so on until n.
00:22
And you may, many of you should know this formula already is an n times n plus 1 over 2.
00:30
So fn is basically this thing.
00:34
We want to make it like in recursive form.
00:40
And it should be quite obvious.
00:44
We have to find f1 first and foremost f1 will be one, right? because it's a sum of one term, just one.
00:53
Now for fn, how do we use the previous term? well, the definition gave it all away already...