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WAEC Further Mathematics 2010 Question 25

Question 25

Vectors

P, Q, R, S are points in a plane such that PQ = 8i − 5j, QR = 5i + 7j, RS = 7i + 3j and PS = xi + yj. Find (x, y).

  1. A.(−6, −15)
  2. B.(6, 5)
  3. C.(20, 5)
  4. D.(20, 15)
Show the answer and explanation

Answer: C ((20, 5))

Explanation

PS = PQ + QR + RS = (8 + 5 + 7)i + (−5 + 7 + 3)j = 20i + 5j, so (x, y) = (20, 5).