Solve sigma_{s}=C_{3}(n)sigma=frac{C_{3}(n)}{C_{2}(n)}

$$\sigma _ { s } = C _ { 3 } ( n ) \sigma = \frac { C _ { 3 } ( n ) } { C _ { 2 } ( n ) }$$

Evaluate (complex solution)

$$\sigma _{s}=C_{3}n\sigma \text{ and }C_{3}n\sigma =\frac{C_{3}}{C_{2}}$$

Solve for σ_s

$$\left\{\begin{matrix}\sigma _{s}=\frac{C_{3}}{C_{2}}\text{, }&\sigma \neq 0\text{ and }n\neq 0\text{ and }C_{2}=\frac{1}{n\sigma }\\\sigma _{s}=0\text{, }&C_{3}=0\text{ and }C_{2}\neq 0\text{ and }n\neq 0\end{matrix}\right.$$

Solve for σ

$$\left\{\begin{matrix}\sigma \in \mathrm{R}\text{, }&\sigma _{s}=0\text{ and }C_{3}=0\text{ and }n\neq 0\text{ and }C_{2}\neq 0\\\sigma =\frac{1}{C_{2}n}\text{, }&\sigma _{s}=\frac{C_{3}}{C_{2}}\text{ and }C_{3}\neq 0\text{ and }C_{2}\neq 0\text{ and }n\neq 0\end{matrix}\right.$$