Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 2 - Section 2.1 - Functions - Exercises - Page 157: 67

Answer

The domain of this function is $(-\infty,0]\cup[6,\infty)$

Work Step by Step

$g(x)=\sqrt[4]{x^{2}-6x}$ This function is not defined for negative numbers. Its domain can then be found by solving the following inequality: $x^{2}-6x\ge0$ Find the intervals. Take out common factor $x$ from the left side: $x(x-6)\ge0$ The factors are $x$ and $x-6$. Set them equal to $0$ and solve for $x$: $x=0$ $x-6=0$ $x=6$ The factors are zero when $x=0,6$. These numbers divide the real line into the following intervals: $(-\infty,0)$ $,$ $(0,6)$ $,$ $(6,\infty)$ Elaborate a diagram, using test points to determine the sign of each factor in each interval: (refer to the attached image below) It can be seen from the diagram that the inequality is satisfied on the intervals $(-\infty,0)$ and $(6,\infty)$. Also, the inequality involves $\ge$, so the endpoints of these intervals also satisfy the inequality. The domain of this function is $(-\infty,0]\cup[6,\infty)$
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