Question

z=f(x-y)

Answer 1

We have,

z = f(x-y)

Partially derivate w.r.t 'x'

$\dfrac{\delta z}{\delta x} = f'(x-y)$

Now, partially derivate w.r.t 'y'

$\dfrac{\delta z}{\delta y} = -f'(x-y)$