00:01
So i want to graph the function y equals 4 times x on the interval 0 to 2.
00:10
So on the interval 0 to 2, at 0 the function is 2, at 2 the function is 8.
00:20
So that's going to look like this.
00:22
And if i want to find that region under the curve, then i'm just going to drop this segment.
00:29
So what i'm looking for is this area, right? that exact area.
00:36
So that is a triangle, and the area is half base times height.
00:43
So that base and height happen right here where the right angle forms.
00:49
So half, my base is two.
00:51
Now i need my height.
00:53
My height is the value of the function when i put into, so my height is eight.
00:58
So that is going to give me half of two is one.
01:02
That's going to be eight square units.
01:06
So that's my area using geometry.
01:11
Now i want to use ramon's sum with four sub -intervals.
01:16
So 2 minus 0 divided by 4 means that each of my sub -intervals is going to be a half in length.
01:25
So if you think about that, you're starting at 0, you're going out.
01:30
To two and you want four of these.
01:32
So you want 0 .5, 1, and 1 .5.
01:39
Now we want to use a left endpoint.
01:44
So we want 0 .5, 1, and 1 .5.
01:49
F of 0 is 0, f of 0, f of 0, 5 is 2, f of 1 .5 is 2, f of 1 is 4, and f of 1 .5 is six...