cele 5 reguli fundamentale la a fi un sigma

cele 11 reguli fundamentale la a fi un sigma

<tex> regula sigma 1: \text{sol}_{1,2} = \frac{-b \pm \sqrt{\Delta}}{2\cdot a} </tex>
<tex> regula sigma 2: f'(c)=\frac{f(a) - f(b)}{a - b} </tex>
<tex> regula sigma 3: C_n=\frac{1}{n + 1} \cdot \binom{2 \cdot n}{n} </tex>

<tex> regula sigma 6: |X/G| = \frac{1}{|G|} \sum_{g \in G}|X^g| </tex>
<tex> regula sigma 7: \frac{2}{\frac{1}{a} + \frac{1}{b}} \leq \sqrt{a \cdot b} \leq \frac{a + b}{2} \leq \sqrt{\frac{a^2 + b^2}{2}}</tex>
<tex> regula sigma 8: \frac{AC}{CD} = \frac{AB}{BD}, \Delta ABC \text{ cu } \angle BAD = \angle DAC  </tex>

<tex> regula sigma 9: \sum^{n}_{0}\binom{n}{i} = 2^n</tex>
<tex> regula sigma 10: AH = 2R \cdot \cos{a}</tex>
<tex> regula sigma 11: A = i + \frac{p}{2} + 1 </tex>