fg

\begin{array}{c} a_1x+b_1y+c_1z=d_1 \\ a_2x+b_2y+c_2z=d_2 \\ a_3x+b_3y+c_3z=d_3 \end{array} \begin{align}a^3+b^3&=c^3\end{align} \begin{align}a^2+b^2&=c^2\end{align} \begin{cases}{c} a_1x+b_1y+c_1z=d_1 \\ a_2x+b_2y+c_2z=d_2 \\ a_3x+b_3y+c_3z=d_3 \end{cases} \begin{align}\left \lbrace \sum_{i=0}^n i^2 = \frac{(n^2+n)(2n+1)}{6} \right\rbrace\tag{1.2}\end{align} \begin{align} \sqrt{37} & = \sqrt{\frac{73^2-1}{12^2}} \\ & = \sqrt{\frac{73^2}{12^2}\cdot\frac{73^2-1}{73^2}} \\ & = \sqrt{\frac{73^2}{12^2}}\sqrt{\frac{73^2-1}{73^2}} \\ & = \frac{73}{12}\sqrt{1 – \frac{1}{73^2}} \\ & \approx \frac{73}{12}\left(1 – \frac{1}{2\cdot73^2}\right) \end{align}