If the matrix $A = \begin{bmatrix} 4 & 1 \\ 3 & 2 \end{bmatrix}$ is expressed as the sum of a symmetric matrix B and a skew symmetric matrix C then which of the following relations is correct?

If $A$ is a non-singular matrix and $A^2 - A + I = 0$, then $A^{-1} = \ldots$

The value of $3\tan^{-1}\left(\dfrac{1}{2}\right) = \ldots$

If $f(x) = \dfrac{x+2}{x^2-3x+1}$, then the values of $x$ for which $f(x)$ is not defined are