passwella.
Menu

WAEC Further Mathematics 2017 Question 17

Question 17

Matrices and Determinants

If B = (2 5 / 1 3), find B−1. (Matrices written row by row; / separates the rows.)

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

Answer: C ((3 −5 / −1 2))

Explanation

|B| = 6 − 5 = 1. B⁻¹ = (3 −5 / −1 2): swap the diagonal and change the signs of both off-diagonal entries.