Your work is correct!
The looks like they differentiated with respect to x . . . but even that is wrong.If , find
a) the partial derivative of with respect to
b) the partial of with respect to
The method I am using is to treat all x's as constants and to take the derivative of all y's.
For a) I get:
. . . . . which matches the book's answer.
For b) I use the same approach.
If , then should be:
. . . . . Correct!
The book, however, gives the answer as: ??
Am I missing something? . . . Not a thing!
If , then:
Since , then
Their answer doesn't match anything in the problem!
. . It must be just one more typo on their part.