Hi all,

my homework questions states "f(x,y)=sin(x-y) at the point (-3,-3)".

- I distributed sin, and obtained sinx-siny
- holding y constant and differentiating with respect to x, i obtain fx(x,y)=cosx
- the derivative of cos(x) is xcos(x), or -3cos(-3)
- holding x constant and differentiating with respect to y, i obtain fy(x,y)=-cosx
- the derivative of -cos(x) is 3 cos(-3)

for some reason, my answers are wrong. I was wondering if someone could help me walk through the steps. Thank you in advance.