F(x) = 2x/arctgx

To analyze the function \( F(x) = \frac{2x}{\arctan x} \), we can consider several aspects such as its domain, continuity, limits, and potential derivatives if you're looking to find critical points or analyze its behavior. ### 1. **Domain**: The function \( F(x) \) is defined for all \( x \) except where \( \arctan x = 0 \). The function \( \arctan x \) is zero at \( x = 0 \). Therefore, the function has a potential issue (undefined) at that point. The domain is all real numbers except \( x = 0 \): \[ \text{Domain: } x \in \mathbb{R} \setminus \{0\} \] ### 2. **Limits**: Let's calculate limits as \( x \) approaches 0 from the positive and negative sides: - As \( x \to 0^+ \): \[ \lim_{x \to 0^+} F(x) = \lim_{x \to 0^+} \frac{2x}{\arctan x} = \lim_{x \to 0^+} \frac{2x}{x} = 2 \] (using the fact that \( \arctan x \approx x \) for small \( x \)) - As \( x \to 0^- \): \[ \lim_{x \to 0^-} F(x) = \lim_{x \to 0^-} \frac{2x}{\arctan x} = \lim_{x \to 0^-} \frac{2x}{x} = 2 \] Since the left-hand and right-hand limits as \( x \) approaches 0 both equal 2, we conclude: \[ \lim_{x \to 0} F(x) = 2 \] ### 3. **Behavior at Infinity**: - As \( x \to +\infty \): \[ \lim_{x \to +\infty} F(x) = \lim_{x \to +\infty} \frac{2x}{\frac{\pi}{2}} = \frac{4x}{\pi} \rightarrow +\infty \] - As \( x \to -\infty \): \[ \lim_{x \to -\infty} F(x) = \lim_{x \to -\infty} \frac{2x}{-\frac{\pi}{2}} = -\frac{4x}{\pi} \rightarrow +\infty \] ### 4. **Derivatives**: If you are interested in the derivatives, we can apply the quotient rule: \[ F'(x) = \frac{[\arctan x \cdot 2 - 2x \cdot \frac{1}{1+x^2}]}{(\arctan x)^2} \] This expression can be simplified to analyze critical points or concavity. ### Summary The function \( F(x) = \frac{2x}{\arctan x} \) is defined everywhere except at \( x = 0 \), has limits of 2 as \( x \) approaches 0 from either side, increases without bound as \( x \) approaches \( \pm \infty \), and can be further analyzed using derivatives. If you have specific questions or need further analysis (like plotting or finding extrema), feel free to ask!