Why is it that the derivative of y=f(x) with respect to y is 0? Such as the derivative of y=x with respect to y..which is 0.

Question

anonymous · Answer

the derivative of f(x) with respect to y means, how much does f(x) change as y changes.  But f(x) is not a function of y (it is a function of x) so it doesn't change as y changes.  The change is 0, hence the derivative is 0.

anonymous · Answer

But y==f(x) so if I want dy/dy, that would be the change in y as y changes. If y changes by some amount, y will also change by some amount. So this really amounts to df(x)/df(x) which would just be 1. Why does this logic fail?

anonymous · Answer

Actually, I was wrong. Well initially I was wrong. The answer should be one for the reason I stated above. Also, I checked on wolfram alpha. http://www.wolframalpha.com/input/?i=what+is+the+derivative+of+y+with+respect+to+y+when+y%3Df%28x%29%3F