Determinant of a 2 × 2 matrix

Exercise and reference answers

Questions

1. Question

   |A| for a 2 × 2 matrix equals

   Choices

   1. a₁₁a₂₂ − a₁₂a₂₁
   2. a₁₁a₂₁ − a₁₂a₂₂
   3. a₁₁a₂₂ + a₁₂a₂₁

   Correct choice

   a₁₁a₂₂ − a₁₂a₂₁

2. Question

   Determinant of [a₁₁] (a 1 × 1 matrix)

   Choices

   1. |a₁₁| as absolute value
   2. a₁₁
   3. 1

   Correct choice

   a₁₁

3. Question

   Expanding a 3 × 3 determinant is easiest along

   Choices

   1. always the first row
   2. always the leading diagonal
   3. the row or column with the most zeros

   Correct choice

   the row or column with the most zeros

Explanation