Example

Example: Evaluating the Determinant of a 2×22 \times 2 Matrix

To evaluate the determinant of a 2×22 \times 2 matrix, write the determinant with vertical lines, then subtract the products of its diagonals. For example, to evaluate the determinant of the matrix [4−23−1]\begin{bmatrix} 4 & -2 3 & -1 \end{bmatrix}, first write it as ∣4−23−1∣\begin{vmatrix} 4 & -2 3 & -1 \end{vmatrix}. Next, subtract the product of the bottom-left and top-right entries from the product of the top-left and bottom-right entries:

(4)(−1)−(3)(−2)(4)(-1) - (3)(-2)

Simplifying this expression yields −4−(−6)-4 - (-6), which equals −4+6=2-4 + 6 = 2. Thus, the determinant is 22. Similarly, the determinant of [−3−4−20]\begin{bmatrix} -3 & -4 -2 & 0 \end{bmatrix} is evaluated as (−3)(0)−(−2)(−4)(-3)(0) - (-2)(-4), which simplifies to 0−8=−80 - 8 = -8.

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Updated 2026-06-29

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