$$ \begin{align*} \textbf{Izračunaj ove izraze } \&a) X^{2} - X \sqrt{X^{2}- 6 X+5} = 15 X ^{2}\&b) X^{2} - 15 x + \sqrt{x^{2}-2x+ 24 } = 0\&c) \binom{21}{x}\sum_{x}^{x+12} ( X+2X - 15 )\&d) X^{3} - 15 X - 15 \&Marko
Darko \end{align*} $$