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 1: 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 4: \sum^{n}_{1}i = \frac{n \cdot (n + 1)}{2}  </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>

<tex> regula sigma 12: (\sum^{n}_{1}{a_i \cdot b_i}) ^ 2 \leq (\sum^{n}_{1}{a_i ^ 2})\cdot (\sum^{n}_{1}{b_i ^ 2})</tex>
<tex> regula sigma 13: \sum^{n}_{1}{\frac{a_i ^ 2}{b_i}} \geq \frac{ (\sum^{n}_{1}{a_i} ^ 2) }{0}</tex>