Evaluate $2 \times 2$ determinant. $$\left| \begin{array} { c c }
- 3 & 1 \
9 & 7
\end{array} \right|$$
A) -30
B) -20
C) 20
D) 30

Name: Evaluate $2 \times 2$ determinant. \[\left| \begin{array} { c c } - 3 & 1 \\ 9 & 7 \end{array} \right|\] A) -30 B) -20 C) 20 D) 30
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Question

Evaluate $2 \times 2$ determinant. $$\left| \begin{array} { c c } 
- 3 & 1 \
9 & 7
\end{array} \right|$$
A) -30
B) -20
C) 20
D) 30

Quizplus · Accepted Answer

The determinant of a $2 \times 2$ matrix $\left| \begin{array} { c c } a & b \ c & d \end{array} \right|$ is calculated as $ad - bc$. Here, it is $(-3)(7) - (1)(9) = -21 - 9 = -30$.

Evaluate 2×22 \times 22×2 Determinant ∣−3197∣\left| \begin{array} { c c } - 3 & 1 \\9 & 7\end{array} \right|​−39​17​​

Evaluate $2 \times 2$ Determinant $\left| \begin{array} { c c } - 3 & 1 \\9 & 7\end{array} \right|$