Вопрос:

Решите неравенство: ((x^2+4x)/(x+2))^2-(x^2+4x)/(x+2)-6<=0.

Ответ:

\[\left( \frac{x^{2} + 4x}{x + 2} \right)^{2} - \frac{x^{2} + 4x}{x + 2} - 6 \leq 0\]

\[t = \frac{x^{2} + 4x}{x + 2}\]

\[t^{2} - t - 6 \leq 0\]

\[(t - 3)(t + 2) \leq 0\]

\[- 2 \leq t \leq 3 \Longrightarrow\]

\[\Longrightarrow - 2 \leq \frac{x^{2} + 4x}{x + 2} \leq 3\]

\[\left\{ \begin{matrix} \frac{x^{2} + 4x}{x + 2} \geq - 2 \\ \frac{x^{2} + 4x}{x + 2} \leq 3\ \ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ \ }\]

\[\left\{ \begin{matrix} \frac{x^{2} + 4x + 2 \cdot (x + 2)}{x + 2} \geq 0 \\ \frac{x^{2} + 4x - 3 \cdot (x + 2)}{x + 2} \leq 0 \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ }\]

\[\left\{ \begin{matrix} \frac{x^{2} + 4x + 2x + 4}{x + 2} \geq 0 \\ \frac{x^{2} + 4x - 3x - 6}{x + 2} \leq 0 \\ \end{matrix} \right.\ \]

\[\left\{ \begin{matrix} \frac{x^{2} + 6x + 4}{x + 2} \geq 0 \\ \frac{x^{2} + x - 6}{x + 2} \leq 0\ \ \\ \end{matrix} \right.\ \text{\ \ \ \ \ \ \ \ }\]

\[\left\{ \begin{matrix} \frac{\left( x + 3 - \sqrt{5} \right)\left( x + 3 + \sqrt{5} \right)}{x + 2} \geq 0 \\ \frac{(x - 2)(x + 3)}{x + 2} \leq 0\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]


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