TeX джерело:

\frac{{{x^2} + 4x + 3}}{{{x^2} + 2x + 1}} = 0;\quad \left\{ \begin{array}{l}{x^2} + 4x + 3 = 0,\\{x^2} + 2x + 1 \ne 0;\end{array} \right.\quad \left\{ \begin{array}{l}x = - 3,x = - 1,\\x \ne - 1.\end{array} \right.