How Can You Prove a Symmetric Derivative Property for a Continuous Function?

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Let f be continuous on [0,1] and differentiable on (0,1) such that f(0)=f(1), prove that there exist a 0 < c < 1 such that f\acute{}(1-c) = -f\acute{}(c).

thanks for any suggestions.
 
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Just from the givens it made me think of MVT...
 
That was my first impression but it seems to be a little trickier than that.
 
johnson12 said:
That was my first impression but it seems to be a little trickier than that.

It's a little more complicated, but not much. Define g(x)=f(x)+f(1-x). g(0)=g(1), right?
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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