Let $A,B:E\to E$, where $E$ is a finite dimensional vector space, be two linear operators such that all of the eigenvalues are real numbers.
If $AB=BA$, prove that there exists a basis in which both the matrices of $A$ and $B$ are triangular.
Let $A,B:E\to E$, where $E$ is a finite dimensional vector space, be two linear operators such that all of the eigenvalues are real numbers.
If $AB=BA$, prove that there exists a basis in which both the matrices of $A$ and $B$ are triangular.