00:01
Function and we are asked to find the absolute max and minima of this function with the given domain.
00:06
So here we are told that x is between the values of zero and one and that y is also between the values of zero one.
00:13
So here we're going to have this box that we are looking at.
00:20
And i'm going to go ahead and label my vertices.
00:25
So to go about this problem, there are several places where these absolutely extreme may can happen.
00:32
So first, i'm going to go about this problem.
00:32
Look at my boundary points, and then i'm going to look at my interior points and see where i get my biggest and smallest number.
00:40
And we're going to do the same process that we've done in previous problems.
00:45
So i'm going to first look at my line segment, oa.
00:53
So looking at that, my x value is fixed at zero, so it's going to be the same thing as f of 0y.
01:00
And so when i plug in 0 for x into this equation, i get negative 24 y squared.
01:07
And now just like before, to get our extreme value i'm going to take the derivative and set it equal to zero.
01:15
So when i take the derivative of this i get negative 48 y and so therefore y is equal to zero and x is equal to zero.
01:27
However, that was already one of my endpoints.
01:30
So now i'm just going to find the values of my endpoints so that's also where extreme values can happen.
01:39
So when i plug in zero into my function i just get zero and then when i plug in zero for x and one in for y i get negative 24 okay then i'm just repeat this process with all of the lines like all of the side lengths so for ab now y is fixed at 1 x is with the one that's changing so my f of x y is going to equal to f of x1 so plugging in one for y into this equation i end up with 40 x minus 32 x cubes minus 24 and then taking the derivative of this i get 48 minus 96 x squared is equal to zero and so if you solve that for x you should get the x is equal to plus or minus one over the square root of two or y is equal to one so these are our points or interior points of that line however, the negative is not an interior point.
02:56
It's not in our domain, so we're going to forget the negative and just finds the value of the positive, and then also my endpoints.
03:07
I already found this end point, so i just need to find it.
03:11
F of 1 .1.
03:13
So the value of this function at this point is going to be 16 times the square root of 2 minus 24, and at 1 -1, it's going to be negative 8.
03:27
Okay, moving on, i'm going to go to bc.
03:32
So here, my x is fixed at 1.
03:37
Y is the one that's changing.
03:38
So it's going to be the same thing as f of 1.
03:42
Or 1y, sorry.
03:47
And when i plug in 1 for x, i get 48.
03:52
Y minus 32, minus 24 y squared...