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JAMB Mathematics 2022 past questions and answers

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

Question 12

Algebraic Expressions

Make C the subject of the formula W = 1 − a/5 (b + 3/7 c)

  1. A.C = −7/3[b + 5/a(w − 1)]
  2. B.C = −[76/3 + 5/a(w − 1)]
  3. C.C = −7/3[b + (5w − 1)/a]
  4. D.C = 7/3[b − 5/a(w − 1)]
Show the answer and explanation

Answer: A (C = −7/3[b + 5/a(w − 1)])

Explanation

a/5 (b + 3c/7) = 1 − W, so b + 3c/7 = 5(1 − W)/a. Then 3c/7 = −[b + 5(W − 1)/a], so c = −7/3[b + 5/a(W − 1)].

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Question 14

Matrices and Determinants

Find the value of P if |−2 1 1; 2 1 P; 1 2 −1| = 23 (rows of the determinant separated by semicolons)

  1. A.1
  2. B.−21/2
  3. C.16/5
  4. D.3
Show the answer and explanation

Answer: C (16/5)

Explanation

Expand along the top row: −2(−1 − 2P) − 1(−2 − P) + 1(4 − 1) = 2 + 4P + 2 + P + 3 = 7 + 5P. Setting 7 + 5P = 23 gives P = 16/5.

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Question 17

Algebraic Expressions

Factorize completely 4a2 − 12ab − c2 + 9b2?

  1. A.4a(a − 3b) + (3b − c)2
  2. B.(2a + 3b − c)(2a + 3b + c)
  3. C.4a(a − 3b) + (3b + c)2
  4. D.(2a − 3b − c)(2a − 3b + c)
Show the answer and explanation

Answer: D ((2a − 3b − c)(2a − 3b + c))

Explanation

Group 4a² − 12ab + 9b² = (2a − 3b)². Then (2a − 3b)² − c² is a difference of two squares: (2a − 3b − c)(2a − 3b + c).

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Question 28

Commercial Arithmetic

If the interest of ₦150.00 for 2½ years is ₦4.50. Find the interest on ₦250.00 for 6 months at the same rate?

  1. A.₦7.50
  2. B.₦1.50
  3. C.₦15.00
  4. D.₦18.00
Show the answer and explanation

Answer: B (₦1.50)

Explanation

Rate = 100 × 4.50/(150 × 2.5) = 1.2% per year. Interest on ₦250 for ½ year = 250 × 1.2 × 0.5/100 = ₦1.50.

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