\[\frac{x^{2} - 16}{x^{3} + 4x^{2} - 3x - 12} = 0\]
\[\frac{(x - 4)(x + 4)}{x^{2}(x + 4) - 3 \bullet (x + 4)} = 0\]
\[x - 4 = 0\]
\[x = 4\]
\[Ответ:4.\]