Let r > 0 .f: (0)→R and suppose there exists an α >1 such that |f (x)| < for all x Є (0)
Prove that f is differentiable at 0

2. Originally Posted by mahmodmg
Let r > 0 .f: (0)→R and suppose there exists an α >1 such that |f (x)| < for all x Є (0)
Prove that f is differentiable at 0
What do you mean by (0)? An open neighborhood of 0? And please specifiy the condition $\vert f(x) \vert <$