If $\alpha, \beta, \gamma$ satisfy the equation $\left|\begin{array}{lll}x & 1 & 1 \\ 1 & x & 1 \\ 1 & 1 & x\end{array}\right|=0$, then
(a) $\alpha+\beta+\gamma=0$
(b) $\alpha^{2}+\beta^{2}+\gamma^{2}=6$
(c) $\alpha^{3}+\beta^{3}+\gamma^{3}=-6$
(d) $\alpha^{4}+\beta^{4}+\gamma^{4}=18$