00:01
So we wish to find for what values of a this sequence converges.
00:06
Well, i'm going to take the sumands and do some reverse partial fractions to it.
00:11
Multiplying this by n plus 4 over n plus 4 and this by n plus 2 over n plus 2, we have a times n plus 4 minus n plus 2 is equal to n plus 2 times n plus 4, which the numerator here is going to be a linear function of a minus 1 times n plus 4 minus 2 is going to be plus 2 divided by n squared plus 6n minus 8.
00:50
So that's good, that's nice.
00:54
So, we can split this up now into a little bit.
01:01
A minus 1 times n over n squared plus 6n minus 8 plus 2 over n squared plus 6n minus 8.
01:15
And this is, of course, infinite sum.
01:20
And let's think about this here.
01:22
So this part of this, these terms are always going to converge, right? because this, you can compare it to a p -series.
01:35
N squared over, so 1 over n squared over 1 over, not 1 over anything, but rather 2 over n squared plus 6n minus 8.
01:54
It's going to be n squared plus 6n minus 8 over n squared equals 1 plus 6 over n minus 8 over n squared...