Continuity At Minus One
1. **Problem Statement:** We are given a piecewise function:
$$f(x)=\begin{cases} \frac{2}{x^2} & \text{for } x \leq -1 \\\ \frac{x+3}{\cos(x+1)} & \text{for } -1 < x < \frac{\pi - 2}{2} \end{cases}$$
We need to determine if $f$ is continuous at $x = -1$.
2. **Continuity Definition:** A function $f$ is continuous at $x = a$ if:
$$\lim_{x \to a^-} f(x) = \lim_{x \to a^+} f(x) = f(a)$$
3. **Evaluate $f(-1)$:** Since $x = -1$ falls in the first case ($x \leq -1$),
$$f(-1) = \frac{2}{(-1)^2} = \frac{2}{1} = 2$$
4. **Left-hand limit as $x \to -1^-$:** Using the first case,
$$\lim_{x \to -1^-} f(x) = \lim_{x \to -1^-} \frac{2}{x^2} = \frac{2}{(-1)^2} = 2$$
5. **Right-hand limit as $x \to -1^+$:** Using the second case,
$$\lim_{x \to -1^+} f(x) = \lim_{x \to -1^+} \frac{x+3}{\cos(x+1)}$$
Evaluate numerator and denominator at $x = -1$:
$$x+3 = -1 + 3 = 2$$
$$\cos(x+1) = \cos(0) = 1$$
So,
$$\lim_{x \to -1^+} f(x) = \frac{2}{1} = 2$$
6. **Conclusion:** Since
$$\lim_{x \to -1^-} f(x) = \lim_{x \to -1^+} f(x) = f(-1) = 2,$$
$f$ is continuous at $x = -1$.
**Final answer:** A Yes