Question

partial deriv question

Answer 1

fy is incorrect, not sure if it's a calculation or a simplification issue

Answer 2

Please do not comment unless you are making a genuine, informed attempt to answer the question. Thank you for being considerate of other users.

Answer 3

@SmokeyBrown plz

Answer 4

Oh, don't you use the Power Function rule for this one?

Answer 5

yeah that's what i did

Answer 6

When you take the derivative of the inside of the square root (y^2+4z^2), did you get
(2y +4)?

Answer 7

shouldn't it just be 2y? z is a constant so it's derivative in this case is 0

Answer 8

Oh, that's true. Hm.

Answer 9

Ok, let me try this step by step.
If you write the inside of the square root as a separate function g(y), you get g(y)=y^2+4z^2
And the derivative of that is 2y
Then, we have the original function. Now we're taking the derivative of -g(y)^1/2
That gives us -(g(y)^(-1/2))/2
Then you multiply that by the derivative of g(y), 2y.
And you get -y*(y^2+4z^2)^(-1/2)

Answer 10

Sorry, it looks to me like you did everything right

Answer 11

no worries, I'll just throw this on the course piazza or something

Answer 12

did you ever figure it out? i can take a look if you didn't

Answer 13

Not yet

Answer 14

try rationalizing the denominator (multiplying top and bottom by what you have for the bottom), and see if that's the form it's looking for?

Answer 15

On mobile but will try when I get home

Answer 16

alright finally home gonna try this out

Answer 17

yeah that did the trick, thanks