Let $\alpha$ and $\beta$ be real numbers. Consider a $3 \times 3$ matrix $A$ such that $A ^ { 2 } = 3 A + \alpha I$. If $A ^ { 4 } = 21 A + \beta I$, then\\ (1) $\alpha = 1$\\ (2) $\alpha = 4$\\ (3) $\beta = 8$\\ (4) $\beta = - 8$