Let \( S = \{p_1, p_2, \dots, p_{10}\} \) be the set of the first ten prime numbers. Let \( A = S \cup P \), where \( P \) is the set of all possible products of distinct elements of \( S \). Then the number of all ordered pairs \( (x, y) \), where \( x \in S \), \( y \in A \), and \( x \) divides \( y \), is _________.
The set \( A = S \cup P \) consists of \( S \), the set of the first ten primes, and \( P \), the set of all possible products of distinct elements of \( S \). Thus, \( |A| = 2^{10} - 1 = 1023 \), since there are \( 2^{10} \) subsets of \( S \), excluding the empty subset.
For each \( x \in S \), \( x \) divides exactly half of the elements of \( A \), as for every product that doesn't contain \( x \), there is a corresponding one that does. Hence, for each \( x \in S \), there are 512 elements in \( A \) divisible by \( x \).
Since there are 10 elements in \( S \), the total number of ordered pairs \( (x, y) \) such that \( x \) divides \( y \) is:
\[ 512 \times 10 = 5120. \]
The correct answer is \( \boxed{5120} \).
Let a line passing through the point $ (4,1,0) $ intersect the line $ L_1: \frac{x - 1}{2} = \frac{y - 2}{3} = \frac{z - 3}{4} $ at the point $ A(\alpha, \beta, \gamma) $ and the line $ L_2: x - 6 = y = -z + 4 $ at the point $ B(a, b, c) $. Then $ \begin{vmatrix} 1 & 0 & 1 \\ \alpha & \beta & \gamma \\ a & b & c \end{vmatrix} \text{ is equal to} $
Resonance in X$_2$Y can be represented as
The enthalpy of formation of X$_2$Y is 80 kJ mol$^{-1}$, and the magnitude of resonance energy of X$_2$Y is: