00:01
Okay, we're going to estimate the volume under this z equals xy over this rectangle, x from 0 to 6, and then y from 0 to 4.
00:13
And they want us to cut the x, the x, the x part up into three pieces.
00:17
That's the red lines, and the y part up into two pieces, and that's the green lines.
00:23
So first, we're going to use the upper right corner to find the height.
00:28
And second, we're going to use the midpoint to find the height.
00:32
And notice, we don't care what this looks like.
00:35
What we care about is what it looks like in two dimensions.
00:39
Okay, so we got six rectangles.
00:41
So we'll call this one, one, one, two, three, four, five, six.
00:47
The upper right corner of rectangle one is two -two.
00:53
Z is x times y, so that's four.
00:57
Delta x is two.
00:58
Delta y is two.
00:59
4 times 2 times 2, that's 16.
01:04
And 2, the upper right hand corner is 4 .2.
01:10
So z is 8.
01:11
This is 2 and 2.
01:14
That's 32.
01:16
Next one is 6 .2.
01:20
And so z is 12, 2, 2, 48.
01:26
In the fourth rectangle, the upper right hand corner is 2 .4.
01:32
So z is 8.
01:34
Still 2 and 2 here.
01:37
It's 32.
01:38
And the next one is 4 -4.
01:44
So z is 16, 64.
01:50
And then the sixth one, it is 6 -4.
01:54
So z is 24, 24 times 4.
01:57
Oops, 2 times 2, 96.
01:59
So the estimate of our volume is 10, 20, 28, 2 ,000, 288...