A Hidden-Zero Comparison

Problem

Let f(x)=alnx+1xf(x) = \dfrac{a\ln x + 1}{x} with aRa \in \mathbb{R}, and g(x)=ex1g(x) = \mathrm{e}^x - 1.

1. Discuss the monotonicity of f(x)f(x). 2. If f(e)=2ef(\mathrm{e}) = \dfrac{2}{\mathrm{e}}, prove that g(x)f(x)g(x) \geqslant f(x).

Answer

Solution

Difficulty6/10
Topicsfunctions, Extrema, calculus, Monotonicity, Casework

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