Solve varepsilon=-l_{1}*F_{q}+(h+l_{2})*F=0

$$\varepsilon = - l _ { 1 } \cdot F _ { q } + ( h + l _ { 2 } ) \cdot F = 0$$

Evaluate (complex solution)

$$\epsilon =F\left(h+l_{2}\right)-F_{q}l_{1}\text{ and }F\left(h+l_{2}\right)-F_{q}l_{1}=0$$

Solve for ε

$$\epsilon =0$$

$$\left(h=-l_{2}\text{ and }F_{q}=0\right)\text{ or }\left(F=0\text{ and }F_{q}=0\right)\text{ or }\left(l_{1}=\frac{F\left(h+l_{2}\right)}{F_{q}}\text{ and }F_{q}\neq 0\right)$$

Solve for l_2

$$\left\{\begin{matrix}l_{2}=\frac{F_{q}l_{1}}{F}-h\text{, }&\epsilon =0\text{ and }F\neq 0\\l_{2}\in \mathrm{R}\text{, }&\left(F_{q}=0\text{ or }l_{1}=0\right)\text{ and }\epsilon =0\text{ and }F=0\end{matrix}\right.$$