College Algebra 7th Edition

Published by Brooks Cole
ISBN 10: 1305115546
ISBN 13: 978-1-30511-554-5

Chapter 3, Polynomial and Rational Functions - Chapter 3 Review - Exercises - Page 358: 97

Answer

$\left(-\infty, -2\right) \cup (1, 2)$

Work Step by Step

1. Express the inequality in the form $f(x)<0, f(x)>0, f(x)\leq 0$, or $f(x)\geq 0,$ where $f$ is a Rational function. $\displaystyle \frac{5}{x^3-x^2-4x+4} \lt 0$ $\displaystyle \frac{5}{x^2(x-1)-4(x-1)}\lt0,$ $\displaystyle \frac{5}{(x^2-4)(x-1)}\lt0,$ $\displaystyle \frac{5}{(x-2)(x+2)(x-1)}\lt0,$ 2. The cut points are: $\displaystyle \frac{5}{(x-2)(x+2)(x-1)}= 0$ $x=-2$ or $x=2$ or $x=1$ 3. Make a table or diagram: use the test values to make a table or diagram of the sign of each factor in each interval. 4. Test each interval's sign of $f(x)$ with a test value, $\begin{array}{llll} Intervals: & a=test.v. & f(a),signs & f(a) \lt 0 ? \\ & & \displaystyle \frac{5}{(a-2)(a+2)(a-1)} & \\ (-\infty,-2) & -10 & \frac{}{(-)(-)(-)}=(-) & T\\ (-2,1) & 0 & \frac{}{(-)(+)(-)}=(+) & F\\ (1, 2) & \frac{3}{2} & \frac{}{(-)(+)(+)}=(-) & T\\ (2,\infty) & 10 & \frac{}{(+)(+)(+)}=(+) & F\\ \end{array}$ 5. Write the solution set, selecting the interval or intervals that satisfy the given inequality. If the inequality involves $\leq$ or $\geq$, include the boundary points. Solution set: $\left(-\infty, -2\right) \cup (1, 2)$
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