$$ \begin{align*} \textbf{Izračunaj ove izraze } \\ &\ a) 11 X^{2}-\frac{1}{ 11 } Y^{2} = 0 \\ &\ b) 6 X^{2}-\frac{1}{ 5 } Y^{2} = 0 \\ &\ c) \binom{21}{x}\sum_{x}^{x+12} ( X+2X - 16 ) \\ &\ d) X^{3} - 16 X - 16 + 6 X^{2}-\frac{1}{ 5 } Y^{2} = 0 \\ &\ \end{align*} $$