00:01
Hi there, so for this problem we know that the function k is just simply x to the y times z to the 3.
00:19
And for this we are given that x is equal to r times x to the square, then y is s plus r times t, and z is just the product between r, s, and t, and this plus 2.
00:38
So we are asked to calculate the partial derivative of this function with respect to s.
00:49
Okay, so this partial derivative can be written as follows.
00:55
The partial derivative of the function k with respect to x times the partial derivative of x with respect to s, then this plus the partial derivative of k with respect to y times the partial derivative of y with respect to, in this case with respect to s.
01:16
Okay, and finally the partial derivative of k with respect to z this times the partial derivative of z with respect to s.
01:27
So let's do those partial derivatives separately.
01:30
So let's start with the partial derivative of k with respect to x.
01:33
Now as you can see the only term that depends on x is this one right here.
01:38
So we treat everything else as a constant.
01:42
So then that will be, we take down the y so that will be then x elevated to y minus one.
01:53
Okay, so that's the derivative with respect to x and then this times z to the three.
02:04
Let's do the partial derivative of k with respect to, well in here we can already substitute the values that we are given for this.
02:18
So we know that y is just s plus r times t, then this times s and that will be elevated to s plus r times t minus one, then c to the three so it'll be r s t plus two and that to this to the three.
02:43
Now let's do the partial derivative of k with respect to y...