Let $A$ be a $2\times 2$ matrix with real entries, which is symmetric. Prove that $A$ is similar over $\Bbb{R}$ to a diagonal matrix.
Real symmetric matrix similar to diagonal matrix
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linear-algebra
matrices
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5wande: welcome to MathSE. I see that this is your first question. So I wanted to let you know a few things about MathSE. We like to know the sources of questions. We also like to know what you've tried on a problem. These sort of pleasantries usually result in more and better answers. Finally, I should add that posting questions in the imperative (i.e. Compute all such, Prove that...) is considered rude by some of the members, so it would be nice of you to change that wording. Thank you. – 2011-09-06