WAEC Mathematics 2019 Objective — Question 11

Question 11 of 145 from the West African Examinations Council (WAEC) Mathematics 2019 Objective paper, with the correct answer and a full explanation.

11. If m:n = 2:1, evaluate (3m²−2n²)/(m²+mn).

A. 4/3
B. 5/3
C. 3/4Correct
D. 3/5

Explanation

If m:n=2:1, then m=2n. Substituting: [3(2n)²−2n²]/[(2n)²+(2n)n] = [12n²−2n²]/[4n²+2n²] = 10n²/6n² = 5/3. (Note: the source key lists the answer as C = 3/4; the worked value from the given substitution is 5/3—this is flagged as an inconsistency in the original source.)

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