00:01
We want to determine whether the sequence a -n is equal to n factorial over n to the end converges or diverges, and if it converges, what it converges to.
00:13
So they give us a hint of comparing this sequence to 1 over n.
00:20
So let's go ahead and write out what this actually is.
00:26
Well, in factorial is 1 times 2, 3, times 4.
00:33
Times n minus 1 times n and into the n is going to be n times n times n times n dot dot n times n so it's going to look something like this here well notice that if we have if we group these numbers like so so if we group two and in so i'm just going to leave one over in by itself because that will always be less than or equal to itself.
01:09
Well, 2 over n, since n is going to at least be bigger than 2 at some point, well, that's going to be less than or equal to 1.
01:22
3 over n is going to be less than or equal to 1, 4 over n is going to be less than or equal to 1, then dot, dot, dot, times n minus 1 over n is going to be less than or equal to 1, and n over in is 1.
01:37
So that will also be less than or equal to 1.
01:39
So we know this function is always bounded above by the function 1 over.
01:46
So we can write a -n is always going to be less than or equal to 1 over n...