Calculus 10th Edition

Published by Brooks Cole
ISBN 10: 1-28505-709-0
ISBN 13: 978-1-28505-709-5

Chapter 3 - Applications of Differentiation - 3.4 Exercises - Page 192: 33

Answer

$$\eqalign{ & {\text{Relative maximum at }}\left( {0,3} \right) \cr & {\text{Relative minimum at }}\left( {2, - 1} \right) \cr} $$

Work Step by Step

$$\eqalign{ & f\left( x \right) = {x^3} - 3{x^2} + 3 \cr & {\text{*Calculate the first derivative}} \cr & f'\left( x \right) = \frac{d}{{dx}}\left[ {{x^3} - 3{x^2} + 3} \right] \cr & f'\left( x \right) = 3{x^2} - 6x \cr & {\text{Set }}f'\left( x \right) = 0 \cr & 3{x^2} - 6x = 0 \cr & 3x\left( {x - 2} \right) = 0 \cr & x = 0,{\text{ }}x = 2 \cr & \cr & *{\text{Calculate the second derivative}} \cr & f''\left( x \right) = \frac{d}{{dx}}\left[ {f'\left( x \right)} \right] \cr & f''\left( x \right) = \frac{d}{{dx}}\left[ {3{x^2} - 6x} \right] \cr & f'\left( x \right) = 6x - 6 \cr & \cr & {\text{Evaluate the second derivative at }}x = 0{\text{ and }}x = 2 \cr & *f''\left( 0 \right) = 6\left( 0 \right) - 6 < 0 \cr & {\text{Then by the second derivative test }}\left( {{\text{Theorem 3}}{\text{.9}}} \right) \cr & f\left( x \right){\text{ has a relative maximum at }}\left( {0,f\left( 0 \right)} \right) \cr & f\left( 0 \right) = {\left( 0 \right)^3} - 3{\left( 0 \right)^2} + 3 = 3 \cr & {\text{Relative maximum at }}\left( {0,3} \right) \cr & *f''\left( 2 \right) = 6\left( 2 \right) - 6 > 0 \cr & {\text{Then by the second derivative test }}\left( {{\text{Theorem 3}}{\text{.9}}} \right) \cr & f\left( x \right){\text{ has a relative minimum at }}\left( {2,f\left( 2 \right)} \right) \cr & f\left( 2 \right) = {\left( 2 \right)^3} - 3{\left( 2 \right)^2} + 3 = - 1 \cr & {\text{Relative minimum at }}\left( {2, - 1} \right) \cr} $$
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