## imagreencat 3 years ago Hey guys! I would just like to ask if my partial differentiating is correct. f(x,y)=xy (sin (4yx^2)) fyx = sin 4yx^2 + (8yx^2)(cos 4yx^2) + (12yx^2)(cos 4yx^2) - 32(x^4)(y^2)(sin 4yx^2) Thanks!

1. ash2326

You have differentiated with respect to x or y?

2. imagreencat

Well, fyx. So I first diff with respect to y then with respect to x. :)

3. TuringTest

it's the mixed derivative? let me check...

4. ash2326

Ok :)

5. TuringTest

$f_x=y\sin(4yx^2)+8x^2y^2\sin(4x^2y)\cos(4x^2y)$I'm typing it out so we can all see if I make a mistake...

6. imagreencat

Fy first. :) Then diff Fy with respect to x.

7. TuringTest

the order shouldn't matter I don't think$f_{xy}=\sin(4yx^2)+4yx^2\cos(4yx^2)+\frac{\partial}{\partial y}[8x^2y^2\sin(4x^2y)\cos(4x^2y)]$

8. imagreencat

Actually in some cases the order does not matter. But in others, it does. Anyway, thank you turing test! :)

9. TuringTest

oh but I have a 16...

10. TuringTest

I'll do it the other way on paper to see if that makes a diff

11. TuringTest

ok I redid it the other way and got the same answer as you sorry for the confusion

12. imagreencat

It's okay Turing Test. I'm sorry for taking some of your time. :))) But, thanks again. I appreciate your effort.

13. TuringTest

no it's my fault for messing up the first time you're welcome