Question

z = f(u) and u = x-y. suppoze dz/dx = -19; find dz/dy

Answer 1

exact problem is in the image

Answer 2

i'm guessing dz/dy will come out to a single number, right?

i got it down to x-y = -19 - dz/dy
or
dz/dy = -19-(x-y)

Answer 3

4n!m0s!ty

Answer 4

wth! @ Kl

Answer 5

spose: z = x-y and calculate dz/dx is my first idea

Answer 6

or maybe:

z = f(u)
\[\frac{dz}{du}=\frac{d}{du}f(u)*\frac{d}{du}u\]

Answer 7

\[\frac{dz}{dx}=\frac{dz}{du}\frac{du}{dx}\]
maybe

Answer 8

\[-19=\frac{d\ f(u)}{du}* 1\]

Answer 9

integrate back up ... and im winging it here and hoping for the best :)

\[-19u = f(u)\]

Answer 10

might be a +c that i never remember to add on

Answer 11

I think the problem can be solved by chain rule

du/dx = 1 and du/dy = -1, when you find the partial derivatives of u

take dz/dx and you get (df(u)/du)*(du/dx), since dz/dx = -19 and du dx = 1, df(u)/du = -19

take dz/dy, which is (df(u)/du)*(du/dy), and substitute the values from above.

dz/dy = 19