If \( 2P(A) = P(B) = \frac{5}{13} \) and \( P(A | B) = \frac{3}{10} \), find \( P(A \cup B) \).
Find matrix \( AB \) if
\[ A = \begin{bmatrix} -1 & 2 & 3 \\ 4 & -2 & 5 \end{bmatrix}, \quad B = \begin{bmatrix} 2 & 1 \\ 6 & 7 \\ 5 & 3 \end{bmatrix} \]
Is the function \( f(x) \) defined by
\[ f(x) = \begin{cases} x + 5, & \text{if } x \leq 1 \\ x - 5, & \text{if } x > 1 \end{cases} \]
continuous at \( x = 1 \)?