Question

Let $f:R\to R$ be such that for all $xϵR$ $(2^{1+x}+2^{1-x}),f(x)$ and $(3^x+3^{-x})$ arein A.P., then the minimum value of f(x) is :

• A. 0
• B. 4
• C. 3
• D. 2

Answer 1

Answer: (C)

$f\left(x\right)=\frac{2\left(2^x+2^{-x}\right)+\left(3^x+3x^{-x}\right)}{2}\ge 3$
$\left(A.M\ge G.M\right)$