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JAMB Mathematics 1988 Question 27

Question 27

Graphs of Functions

The solution of x2 − 2x − 1 = 0 are the points of intersection of two graphs. If one of the graphs is y = 2 + x − x2, find the second graph.

  1. A.y = 1 − x
  2. B.y = 1 + x
  3. C.y = x − 1
  4. D.y = 3x + 3
Show the answer and explanation

Answer: A (y = 1 − x)

Explanation

We need 2 + x − x² = g(x) to be the same as x² − 2x − 1 = 0. So g(x) = 2 + x − x² + (x² − 2x − 1) = 1 − x.