Show that f is not differentiable at (0,0)
83915
Showing that a function is not differentiable
106768
Recognizing that a function has no elementary antiderivative
94193
determine whether $f(x, y) = \frac{xy^3}{x^2 + y^4}$ is differentiable at $(0, 0)$.
144023
Indefinite integral which is not differentiable
62352
Proving a scalar function is differentiable at the origin but that its partial derivatives are not continuous at that point.
138544
For which values of $x$, will $f (x) . f '(x) < 0$?
151958
How to show $f'(0)$ exist and is equal to $1$?
105068
Proving that the function is differentiable and $f'(0)=0$
12556
A non-trivial, non-negative, function bounded below by its derivative with $f(0)=0$?
156839
Functions Which are non differentiable on a Given Set.
8659
How do you show that $e^{-1/x^2}$ is differentiable at $0$?
104263
How to show that $f'(x)<2f(x)$
44129
If $f:\mathbb{R}\rightarrow \mathbb{R}$ is differentiable and $\lim_{x\to \infty } f^\prime(x)=0$ show that $\lim _{x\to \infty } (f(x+1)-f(x))=0$.
107727
$m\{x\in [0,1]:f'(x)=0\}>0$
27888
Why is $|x|$ not differentiable at $x=0$?
35671
Why can a discontinuous function not be differentiable?
21954
A question about $f(x)\equiv 0$