It's too easy question but I'm confused.
Let A matrix is \begin{pmatrix} 5 & 4\\ 4 & 5\\ \end{pmatrix}
Of course it can be diagonalized since it has distinct two eigenvalues.
The question is to find square roots, that is $R^2$=A.
I think there are two possible $R$, $A^\frac{1}{2}$ and $-A^\frac{1}{2}$
However the answer is four. What are the other two?