1. **Problem statement:** Calculate the integral $$\int_{-\infty}^{+\infty} \frac{dx}{x^2 + 2x + 2}$$ and study its convergence.
2. **Rewrite the integrand:** Complete the square in the denominator:
$$x^2 + 2x + 2 = (x+1)^2 + 1$$
3. **Recognize the integral form:** The integral becomes
$$\int_{-\infty}^{+\infty} \frac{dx}{(x+1)^2 + 1}$$
4. **Recall the standard integral formula:** For real $a > 0$,
$$\int_{-\infty}^{+\infty} \frac{dx}{x^2 + a^2} = \frac{\pi}{a}$$
5. **Apply the formula:** Here, $a = 1$, so
$$\int_{-\infty}^{+\infty} \frac{dx}{(x+1)^2 + 1} = \pi$$
6. **Convergence:** The integral converges because the integrand behaves like $1/x^2$ for large $|x|$, which is integrable over $\mathbb{R}$.
**Final answer:**
$$\int_{-\infty}^{+\infty} \frac{dx}{x^2 + 2x + 2} = \pi$$
Integral Quadratic E62929
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