Let $\alpha $ and $\beta $ be two roots of the equation x2 + 2x + 2 = 0 , then $\alpha ^{15}$ + $\beta ^{15}$ is equal to :

Question

Let $\alpha $ and $\beta $ be two roots of the equation x² + 2x + 2 = 0 , then $\alpha ^{15}$ + $\beta ^{15}$ is equal to :