passwella.
Menu

JAMB Mathematics 1986 Question 30

Question 30

Graphs of Functions

At what points does the straight line y = 2x + 1 intersect the curve y = 2x2 + 5x − 1?

  1. A.(−2, −3) and (½, 2)
  2. B.(−½, 0) and (2, 5)
  3. C.(½, 2) and (1, 3)
  4. D.(1, 3) and (2, 5).
Show the answer and explanation

Answer: A ((−2, −3) and (½, 2))

Explanation

2x² + 5x − 1 = 2x + 1 gives 2x² + 3x − 2 = 0 = (2x − 1)(x + 2), so x = ½ or −2. Then y = 2 or −3.