Find at the point (1,-1) for
So I came up with:
After cleaning it up a bit, I got:
So:
Can someone please double check this for me? Thanks
You should not have a "-" on that in the first line so the entire numerator in your derivative should be negative.
Also, I do not see why you call this a "partial" derivative and use rather than . There does not appear to be any other independent variable.