# Math Help - Complex Analysis an entire function

1. ## Complex Analysis an entire function

Help me please with this one:

Let $f(z)$ be an entire function and:

$\left | f(2z)-f(z) \right |\leq c$ $\forall z\in \mathbb{C}$.
Prove that $f$ is constant.

Thanks!

2. ## Re: Complex Analysis an entire function

if f(z) is entire, so does f(2z)-f(z)

3. ## Re: Complex Analysis an entire function

Originally Posted by xxp9
if f(z) is entire, so does f(2z)-f(z)
Thanks, but how to prove it?

4. ## Re: Complex Analysis an entire function

Originally Posted by sinichko
Thanks, but how to prove it?
dONE, THANKS!