Question

find the partial derivative f(x,y) = sin(x-y) at (-1,-1)! xD

Answer 1

\(\frac{\partial f}{\partial x}\)? or \(\frac{\partial f}{\partial y}\)?
$$f=\sin(x-y)\\f_x=\cos(x-y)\\f_y=-\cos(x-y)$$

Answer 2

$$f_x(-1,-1)=\cos(0)=1\\
f_y(-1,-1)=-\cos(0)=-1\\
\nabla f=<1,-1>=i-j$$

Answer 3

thank you so much!!!! :)