QJEEM20Mad94a: JEE Main 2020 Mathematics - Class 11 JEEM20Mad94a Solution: Let ƒ : R R be such that for all x R (2 1+x + 2 1–x ), ƒ(x) and …

Question

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Let ƒ : R

\to

R be such that for all x

\in

R
(2^1+x + 2^1–x), ƒ(x) and (3^x + 3^–x) are in A.P.,
then the minimum value of ƒ(x) is

Accepted Answer

f(x) =

{{2\left( {{2^x} + {2^{ - x}}} \right) + \left( {{3^x} + {3^{ - x}}} \right)} \over 2} \ge 3

As we know, A.M > G.M

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