What form must a function $f$ have if $f(f(x)) = f$ and $f$ is differentiable?
59063
$f(f(x))=f(x)$ question
849
$f$ differentiable, $f(x)$ rational if $x$ rational; $f(x)$ irrational if $x$ irrational. Is $f$ a linear function?
80210
It is posible to have a function $f$ with the following property?
2506
twice differentiable functions
129324
Let $f:[0;1]\to\mathbb R$ be continiously differentiable
111470
Proof of differentiability of $f(x)$
130322
Show that $f(x) = 0$ if $x = 0$ $f(x) = \text{exp}(-1/x^{2})$ if $x \neq 0$ is infinitely differentiable but not analytic at $x_{0} = 0$ `
131357
Prove that $f(x,y)=xy$ is differentiable using the definition
122329
Determine all functions $f(x)$ such that $f(f(x+y))=f(x)+f(y)$
99917
What function satisfies $F'(x) = F(2x)$?
135693
Suppose f is a twice differentiable function with $f(0)=0$ and $f(1)=1$, $f'(0)=f'(1)=0$. Then show that $|f''(x)| > 4$ for some $x$ in $(0,1)$
156536
Defining functions as derivatives
4636
How to show that $f$ is differentiable at $x=0.$
154881
Question on differentiability of a continuous function
134880
Is there a difference between $y(x)$ and $f(x)$
134871
Using definition of derivative to differentiate $f(x)= \sqrt{x}+1$
102549
Check the differentiability of the given function.