WAEC Mathematics 2015 Theory — Question 4
Question 4 of 22 from the West African Examinations Council (WAEC) Mathematics 2015 Theory paper, with the correct answer and a full explanation.
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2(b). The diagram shows a rectangle PQRS from which a square of side X cm has been cut. The area of the shaded portion is 484cm², find the values of X.
Model answer
Area of rectangle PQRS = (10+X+10)×20 = (20+X)(20). Area of square = X². Shaded area = (20+X)(20)−X² = 484 → 400+20X−X²=484 → X²−20X+84=0 → (X−6)(X−14)=0, so X=6 or X=14.
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