Let $f(x)$ be a differentiable function such that $f'(-x) = -f'(x)$ show that $f(-x) = f(x)$.
Unfortunately I am not sure what to do with this simple looking problem. I was having trouble trying to draw any useful conclusions about the function given the property of the derivative... I guess it would've been easier to go the other way around. How is this problem solved?
Thank you in advance for any help!