If A = | 1 2 | | 3 4 |, find det(A).

Practice Questions

Q1
If A = | 1 2 | | 3 4 |, find det(A).
  1. -2
  2. 2
  3. 0
  4. 4

Questions & Step-by-Step Solutions

If A = | 1 2 | | 3 4 |, find det(A).
Correct Answer: -2
  • Step 1: Identify the elements of the matrix A. The matrix A is given as: | 1 2 | | 3 4 |.
  • Step 2: Write down the formula for the determinant of a 2x2 matrix. The formula is: det(A) = (a)(d) - (b)(c), where a, b, c, and d are the elements of the matrix.
  • Step 3: Assign the values from the matrix to the variables in the formula. Here, a = 1, b = 2, c = 3, d = 4.
  • Step 4: Substitute the values into the determinant formula: det(A) = (1)(4) - (2)(3).
  • Step 5: Calculate (1)(4) which equals 4.
  • Step 6: Calculate (2)(3) which equals 6.
  • Step 7: Subtract the second result from the first: 4 - 6.
  • Step 8: The final result is -2, so det(A) = -2.
  • Determinant of a 2x2 Matrix – The determinant of a 2x2 matrix A = | a b | | c d | is calculated using the formula det(A) = ad - bc.
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