WAEC Further Mathematics 2023 Objective — Question 14

Question 14 of 40 from the West African Examinations Council (WAEC) Further Mathematics 2023 Objective paper, with the correct answer and a full explanation.

Given that r=i+2j and n=-i+3j, find |2n-r|.

A. 8.5
B. 5.0Correct
C. 4.0
D. 3.6

Explanation

2n-r = 2(-i+3j)-(i+2j) = (-2i+6j)-(i+2j) = -3i+4j. |2n-r| = sqrt((-3)^2+4^2) = sqrt(9+16) = sqrt(25) = 5.0.

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