WAEC Mathematics 2021 Theory — Question 12
Question 12 of 22 from the West African Examinations Council (WAEC) Mathematics 2021 Theory paper, with the correct answer and a full explanation.
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7(d). Use the graph to find the: (i) roots of the equation 2x²-3x-5=0; (ii) range of values of x for which 2x²-x-2<0.
Model answer
(i) 2x²-x-2=2x+3 ⟹ 2x²-3x-5=0, so the roots are the x-coordinates where the curve and line intersect: x=-1 and x=2.5. (ii) From the graph, the curve lies below the x-axis (y<0) for approximately -0.7<x<1.3.
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