00:01
You want to try to find the area between the graph of the given function, so e to the negative x over the interval negative infinity to e, and we want to find the area between this and the x -axis.
00:23
So this function here will look like, so let's just go ahead and sketch a quick graph of this.
00:37
Maybe i'll write it down here instead.
00:44
So as the numbers get bigger and bigger, so as it goes to infinity, it's going to get very small, and then as it goes to negative infinity is going to get larger and larger.
00:58
So this is what the graph of this is going to look.
01:04
And so since this is all positive, the area between this and the x -axis will just be all of this here up until we reach.
01:15
E.
01:19
So if we want to find this area, we can write this as negative infinity to e of the negative x dx.
01:31
And we'll need to rewrite this as an improper interval.
01:36
So the limit as b approaches negative infinity of b to e to the negative x dx.
01:52
So we have the limit as b as b approaches negative infinity.
01:58
Integrating e to the negative x would be e to the negative x, and then we have to divide by the constant in the power, which would be dividing by negative 1, which is the same thing as multiplying by negative.
02:19
So we have this, and then we want to evaluate this from b to b...