Let $a < b,$ $[a,b]$ be a closed real interval, and $f:[a,b]\to\mathbb R$ a continuous function with $f(a)=f(b)$. Further, let $f$ be differentiable on the open real interval $]a,b[.$ Then there is an $\xi\in ]a,b[$ with $f'(\xi)=0.$
In particular, between any two roots of $f$ there is a root of $f'$.
This theorem is named after Michel Rolle (1652 - 1719).
Proofs: 1
Persons: 1