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JAMB Mathematics 1986 Question 23

Question 23

Graphs of Functions

The curve y = −x2 + 3x + 4 intersects the co-ordinate axes at

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

Answer: D ((0, 4), (4, 0), (−1, 0).)

Explanation

At x = 0, y = 4. For y = 0, x² − 3x − 4 = (x − 4)(x + 1) = 0, so x = 4 or −1. The points are (0, 4), (4, 0) and (−1, 0).