passwella.
Menu

JAMB Mathematics 2013 Question 23

Question 23

Matrices and Determinants

Find the inverse of (5 3; 6 4). (Matrices written row by row.)

  1. A.(2 3/2; −3 −5/2)
  2. B.(2 3/2; −3 5/2)
  3. C.(2 −3/2; −3 −5/2)
  4. D.(2 −3/2; −3 5/2)
Show the answer and explanation

Answer: D ((2 −3/2; −3 5/2))

Explanation

The determinant is 20 − 18 = 2. Swap the diagonal and change the other signs, then halve: ½(4 −3; −6 5) = (2 −3/2; −3 5/2).