Help please, if you could explain it that would be even better.

Let $\mathbf{A} = {\begin{pmatrix} \sqrt{3}/2& -1/2\\ 1/2 & \sqrt{3}/2 \end{pmatrix}}$ Then what is $\mathbf{A}^{2018} \begin{pmatrix} 2 \\ 2 \end{pmatrix}$?