Fórmula 1

[\begin{matrix} 2 \frac{E A}{l} & - \frac{E A}{l} & 0 \\ - \frac{E A}{l} & \frac{E A}{l} + k & - k \\ 0 & - k & 2 \frac{E A}{l} + k \end{matrix}] [\begin{matrix} u_{1} \\ u_{2} \\ u_{3} \end{matrix}] = [\begin{matrix} F \\ k d_{0} \\ - k d_{0} \end{matrix}]

;