passwella.
Menu

JAMB Mathematics 2019 past questions and answers

2 questions. Try each one, then open the answer to check yourself and read the explanation.

Question 17

Matrices and Determinants

Solve for x and y
( 1 1 )( x ) = ( 4 )
( 3 y )( 1 ) ( 1 )

  1. A.x = −3, y = 8
  2. B.x = 8, y = 3
  3. C.x = 3, y = −8
  4. D.x = 8, y = −3
Show the answer and explanation

Answer: C (x = 3, y = −8)

Explanation

The top row gives x + 1 = 4, so x = 3. The bottom row gives 3x + y = 1, so y = 1 − 9 = −8.

Open this question

Question 26

Matrices and Determinants

Find the value of k if
| −2 1 1 |
| 2 1 k | = 23
| 1 2 −1 |

  1. A.1
  2. B.2
  3. C.3
  4. D.16/5
Show the answer and explanation

Answer: D (16/5)

Explanation

Expand along the top row: −2(−1 − 2k) − 1(−2 − k) + 1(4 − 1) = 7 + 5k. So 7 + 5k = 23 and k = 16/5.

Open this question