# no differentiable function

• Jan 9th 2010, 07:36 AM
flower3
no differentiable function
Prove that there is no differentiable function $f:[-1,1] \to \mathbb {R}$ such that $f'(x)=[x]$
• Jan 9th 2010, 07:42 AM
Shanks
Hint:Applying Darboux's theorem! If the statement is true, then it leads to cantradiction to Darboux's theorem.