$$ \begin{align*} \textbf{Izračunaj ove izraze } \&a) x^{2} - 3x = \sqrt{x^{2}-2x+5} \&b) x^{2} - 3x = \sqrt{x^{2}-2x+5} \&c) \binom{21}{x}\sum_{x}^{x+12} \&d) x_{3} - \&\end{align*} $$