$$ \begin{align*} \textbf{Izračunaj ove izraze } \&a) 9 X^{2}-\frac{1}{ 9 } Y^{2} = 0 \&b) 12 X^{2}-\frac{1}{ 7 } Y^{2} = 0 \&c) \binom{21}{x}\sum_{x}^{x+12} ( X+2X - 14 ) \&d) X^{3} - 14 X - 14 + 12 X^{2}-\frac{1}{ 7 } Y^{2} = 0 \&\end{align*} $$