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artix_17
Partial derivative, pls help !! f(w,z)= w(w^2+z^2)^-1 Find f'w
What is the biggest problem for you?
I can't seem to get the answer
Do you know how to calculate the ordinary derivative, not the partial?
Yes, for this question I use product rule, but just can't get the answer
Write here what you've got.
You can draw it using the "Draw" button.
f'w = w X (-1)(w^2+z^2)^-2 X 2w + (w^2+z^2)^-1 (1) = -2w^3 (w^2+z^2) + (w^2+z^2)^-1
= -2w^3 (w^2+z^2)^-2 + (w^2+z^2)^-1
You have to check the last answer very carefully. You are doing this right, but you are making mistakes. Check them.
Which part is the mistake?
f'w = w X (-1)(w^2+z^2)^-2 X 2w + (w^2+z^2)^-1 - This is OK, but this = -2w^3 (w^2+z^2) + (w^2+z^2)^-1 is not. Try to find the common denominator in the first one and subtract the fractions.
oh okay got it, thanks
You answered your question by yourself, I did not help you.