Hello again, everyone, this is Tom from everystepcalculus.com and everystepphysics.com. I’m gonna do partial derivatives now in this video, generally with respect to calculus 2 or 3. Let’s do it. Index 8, get to my menu… Scroll up to get to the P’s quicker. It goes to the bottom of the alphabet, so we get to what we’re looking for, it’s partial derivatives. On the menu you can go second and the titanium second and then these cursers to go page by page. You do that here to get through the menu quicker, and we’re looking at, let’s see, partial fractions, here’s partial derivatives, and I programmed first order or second order; we’re going to do first order in this problem. Z= f (x,y) We’re going to enter our function, that the function given is. You have to press alpha before you enter anything into these entry lines in my programs, okay, so alpha, and then we’re going to press T here, which gives us the arc tangent for Y divided by X I always show you what you’ve entered so you can change it if you made a mistake. So it’s okay, and here’s the partial derivatives, with respect to x, is minus Y divided by X squared plus Y squared, this is a, if you go to my trig identities you’ll see that tangent to the minus 1 is 1 over the quantity of 1 plus x squared. In this case it would be 1 over the quantity 1 plus Y divided by X squared. To get the derivative with respect to X and with respect to Y, it’s this equation here. And then there’s a point A and B that they give you. Press the one for A, is alpha, minus 2. Make sure you know it’s interchanged the minus sign for the negative sign. And then for the B, alpha 7 is given. Again I’ll show you what you’ve entered, and we see that’s okay, and so the problem asks for fx(a,b), which is this right here, replacing the y’s and the x’s for whatever is given here for A and B. And I have to use quotation marks the way the calculator allows me to with programming, but you’re going to use parentheses here anytime you see a quotation here, because you’re substituting X and Y values for the X and Y values in the function. And the answer is -7 over 53. And now if they ask you for F of Y you’d go one step further, and that would be substituting this, you get -2 over 53. Pretty neat, huh? everystepcalculus.com, go to my site and subscribe to me so you can see other videos if you’re interested. Have a good one!