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 Test - Page 360: 12

Answer

$(-\infty, -1] \cup \left(\frac{5}{2}, 3\right]$

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. $\displaystyle x\leq\frac{6-x}{2x-5},$ $\displaystyle x-\frac{6+x}{2x-5}\leq0,$ $\displaystyle \frac{x(2x-5)-6+x}{2x-5}\leq0,$ $\displaystyle \frac{2x^2-4x-6}{2x-5}\leq0,$ $f(x)=\displaystyle \frac{(2x-6)(x+1)}{2x-5}\leq0,$ 2. The cut points are: $\displaystyle\frac{(2x-6)(x+1)}{2x-5} \lt 0$ $x=-1$ or $x=\frac{5}{2}$ or $x=3$ 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, $\begin{array}{llll} Intervals: & a=test.v. & f(a),signs & f(a) \leq 0 ? \\ & & \frac{(2a-6)(a+1)}{2a-5} & \\ (-\infty,-1) & -5 & \frac{(-)(-)}{(-)}=(-) & T\\ (-1,\frac{5}{2}) & 0 & \frac{(-)(+)}{(-)}=(+) & F\\ (\frac{5}{2}, 3) & \frac{8}{3} & \frac{(-)(+)}{(+)}=(-) & T\\ (3,\infty) & 5 & \frac{(+)(+)}{(+)}=(+) & F\\ \end{array}$ 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: $(-\infty, -1] \cup \left(\frac{5}{2}, 3\right]$
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