Medium MCQ +4 / -1 PYQ · JEE Mains 2020

Let ƒ : R $\to$ R be such that for all x $\in$ R
(21+x + 21–x), ƒ(x) and (3x + 3–x) are in A.P.,
then the minimum value of ƒ(x) is

  1. A 2
  2. B 0
  3. C 3 Correct answer
  4. D 4

Solution

f(x) = $${{2\left( {{2^x} + {2^{ - x}}} \right) + \left( {{3^x} + {3^{ - x}}} \right)} \over 2} \ge 3$$ <br><br>As we know, A.M &gt; G.M

About this question

Subject: Mathematics · Chapter: Sequences and Series · Topic: Arithmetic Progression

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