passwella.
Menu

JAMB Mathematics 1989 Question 25

Question 25

Inequalities

Find the range of values of r which satisfies the following inequality, where a, b and c are positive.
r/a + r/b + r/c > 1

  1. A.r > abc/(bc + ac + ab)
  2. B.r > abc
  3. C.r > 1/a + 1/b + 1/c
  4. D.r > 1/abc
Show the answer and explanation

Answer: A (r > abc/(bc + ac + ab))

Explanation

r(bc + ac + ab)/abc > 1. Since a, b, c are positive we can multiply out without changing the sign: r > abc/(bc + ac + ab).