I'm having trouble with the concept. I need to find the partials dz/dy and dz/dx when z=ycos(x-y) and keep coming up with different answers... Can anyone help?
With partial derivatives, you just treat all the variable as constants except the one you're differentiating with respect to.
Your different answers may actually be the same. For instance, don't forget little things like that , and . This could cause your answers to look different but still might all be correct.