Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 7: Transcendental Functions - Section 7.3 - Exponential Functions - Exercises 7.3 - Page 391: 119

Answer

Absolute minimum is $e-2\approx 0.71828$ at $x=1$ Absolute maximum is $1$ at $x=0$

Work Step by Step

$f(x)=e^{x}-2x$ $f'(x)=e^{x}-2$ Critical points: $f'(x)=0\quad $ when $\quad e^{x}=2\Rightarrow x=\ln 2\approx 0.693$ $f(0)=1-0=1$ $f(\ln 2)=2-2\ln 2\approx 0.6137$ $f(1)=e-2\approx 0.71828$ On $(0,\ln 2)$, testpoint $0.5,\qquad f'(0.5)=-0.35...$, f decreases On $(\ln 2,1), $ testpoint $0.8,\qquad f'(0.5)=+0.2255...$, f increases So, Absolute minimum is at $( 1, e-2)$ Absolute maximum is at $(0,1)$ (and a relative maximum at $(\ln 2, 0.6137)$ )
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