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WAEC Further Mathematics 2025 Question 19

Question 19

Vectors

The dot product of p and q is 1 where p = (3/5)i + xj, q = (−5/3)i + (4/7)j. Find the value of x

  1. A.7/2
  2. B.2/7
  3. C.7/4
  4. D.4/7
Show the answer and explanation

Answer: A (7/2)

Explanation

p·q = (3/5)(−5/3) + (4/7)x = −1 + 4x/7 = 1, so 4x/7 = 2 and x = 7/2.