00:03
In this question, we're asked to find the area between two curves.
00:09
The area looks like this in the blue region.
00:13
Ignore the graph underneath it.
00:16
So the first step is we need to find the intersection points.
00:28
We know that they're going to intersect at zero.
00:34
This is simply by observation.
00:38
We can alternatively set the two root quantities equal to each other, and then try and solve.
00:47
And then try and solve that equation through there.
00:58
In other words, we're going to have, also by observation, you'll notice that x equals 1 will also fit in.
01:18
So both of these can be really found by observation, and you don't really need to solve any equations.
01:26
So it's also obvious that the area that the top curve is x times x squared, the square of x squared plus 1.
01:35
And the bottom curve is the other curve.
01:38
And we know that over some region, we know that the area between them is given by integrating the top curve minus the bottom curve.
01:50
So let's plug in all of this information now.
01:53
That means that we have the integral from 0 to 1.
01:59
We'll have x times the square root of x squared plus 1.
02:04
And we're going to actually split this into two integrals, just so we make our life easier.
02:09
Because both of these integrals will have to use a u substitution.
02:16
Both of these i will do in green and blue respectively.
02:22
So for the one in green, i'm going to write it down here.
02:34
We're going to let you be equal to x squared plus 1.
02:38
Du will be equal to 2x dx, and by solving for dx, we'll get that dx is du over 2x...