00:01
Here, we want to find x and y that minimizes s, which is equal to x plus y, that's the sum, if we're told that x times y equals 25.
00:12
So what i need to do is solve for my constraint, that's the x times y equals 25 for one of the variables.
00:18
I'm going to divide by x to get 25 x to the negative 1.
00:22
And i plug that into my objective function, which is s.
00:25
So i get 20, sorry, x plus y, which happens to be 25 y to the negative one.
00:33
Sorry, x to the negative one.
00:36
Now that i have s in terms of just one variable, i can take its derivative.
00:42
So derivative x is one, and the one from the negative one power comes out front.
00:47
So i get negative 25 x to the negative 2...