00:01
Let's start off by showing that this series is convergent.
00:05
So here we would use the alternating series test with bn equals 1 over n 3 to the n.
00:17
This is clearly positive.
00:22
The limited bn is zero.
00:24
You could see that this term goes to infinity.
00:28
So the fraction as a whole goes to zero.
00:34
And bn is decreasing.
00:36
This is clearly true because if you just replace n with n plus 1, that's true.
00:51
So this thing converges by the alternating series test.
01:04
So that takes care of the first part, the first sentence.
01:08
Now we'd like to know how many terms.
01:12
So what's it? it's an end value of the series do we need so that if we take the partial sum, then the error when approximating the actual sum is less than this fraction over here.
01:31
So using the alternating series estimation theorem, the absolute value of the error is less than bn plus 1...