00:01
So for this problem, we're going to be computing a few different riemann sums, and they're going to all be the left -hand sums for n equals 10, 30, and 50 sub -intervals.
00:11
And so we can go ahead and start with our minimum of 10 sub -intervals.
00:15
So we'll go ahead and do this part in red.
00:18
And we know that our first step in calculating a raman sum is going to be finding our delta x or our step size.
00:24
And the way that we do this is we're going to subtract the right end point of our interval.
00:27
So in this case, our interval is from negative 1 to 1.
00:31
So our right end point will be positive 1, and we're going to subtract our left endpoint.
00:37
And then we divide this by whatever our number of sub -intervals is.
00:40
So in this case, our number of sub -intervals, n, is 10.
00:44
So that means that our delta x is going to reduce to 2 over 10 or 1 -5th.
00:50
And from here we're going to be able to calculate what our x sub -i star is.
00:55
And essentially, the way that we figure this out is we just start, at our left endpoint, so in this case negative one.
01:02
We're going to increase it each time by one of our step sizes, which is 1 over 5, times our initial i, because that's going to tell us which step number we're on, minus 1, because of the fact that we have our left endpoints.
01:18
And so from here, we're going to be able to set up our sigma notation.
01:23
So we know that we are going to say that l sub 10 is equal to whatever our delta x is.
01:29
So in this case, one fifth, times sigma going from i is equal to 1, up through our number of sub intervals, which is 10, of f of x of i star...