WAEC Mathematics 2019 Objective — Question 13

Question 13 of 145 from the West African Examinations Council (WAEC) Mathematics 2019 Objective paper, with the correct answer and a full explanation.

13. Solve 4x² − 16x + 15 = 0

A. x=1½ or x=-2½
B. x=1½ or x=2½Correct
C. x=1½ or x=-1½
D. x=-1½ or x=-2½

Explanation

By factorisation: 4x²−16x+15=0. The factors of −10x and −6x work: 4x²−10x−6x+15=0 ⇒ 2x(2x−5)−3(2x−5)=0 ⇒ (2x−3)(2x−5)=0 ⇒ x=3/2 or x=5/2, i.e. x=1½ or x=2½.

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