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JAMB Mathematics 1985 Question 20

Question 20

Graphs of Functions

At what real value of x do the curves whose equations are y = x3 + x and y = x2 + 1 intersect?

  1. A.−2
  2. B.2
  3. C.−1
  4. D.0
  5. E.1.
Show the answer and explanation

Answer: E (1.)

Explanation

x³ + x = x² + 1 gives x(x² + 1) − (x² + 1) = (x − 1)(x² + 1) = 0. Since x² + 1 is never zero, x = 1.