Testeo de entrada

$$ a^2 + b^2 = c^2 $$

$$
\lim_{x \to \infty} \left(1 + \frac{1}{x} \right)^x = e
$$

$$
\int_{-\infty}^{\infty} e^{-x^2} \, dx = \sqrt{\pi}
$$

$$
\sum_{n=1}^{\infty} \frac{1}{n^2} = \frac{\pi^2}{6}
$$

$$
f(x) = \begin{cases}
x^2 & \text{si } x \geq 0 \\
-x^2 & \text{si } x < 0
\end{cases}
$$

$$
A =
\begin{bmatrix}
1 & 2 & 3 \\
4 & 5 & 6 \\
7 & 8 & 9
\end{bmatrix}
$$

La derivada de $$ ( f(x) = \ln(x^2 + 1) ) es ( f'(x) = \frac{2x}{x^2 + 1} ). $$