Problem: If a∣bc∣d=a⋅d−b⋅c\begin{matrix} a \mid b \\ \hline c \mid d \end{matrix} = a \cdot d - b \cdot ca∣bc∣d=a⋅d−b⋅c, what is the value of 3∣41∣2?\begin{matrix} 3 \mid 4 \\ \hline 1 \mid 2 \end{matrix}?3∣41∣2?
Answer Choices:
A. −2-2−2 B. −1-1−1 C. 000 D. 111 E. 222
Solution:
3⋅2−4⋅1=6−4=23 \cdot 2-4 \cdot 1=6-4=23⋅2−4⋅1=6−4=2.
Answer: E\boxed{E}E.
The problems on this page are the property of the MAA's American Mathematics Competitions