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Ch. 3 - Polynomial and Rational Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
All textbooksLial 13th EditionCh. 3 - Polynomial and Rational FunctionsProblem 23
Chapter 4, Problem 23

Solve each polynomial inequality. Give the solution set in interval notation.
(a) -x(x - 1)(x - 2) ≥ 0
(b) -x(x - 1)(x - 2) > 0
(c) -x(x - 1)(x - 2) ≤ 0
(d) -x(x - 1)(x - 2) < 0

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1
Identify the critical points by setting the expression equal to zero: solve \(-x(x - 1)(x - 2) = 0\). The solutions are the values of \(x\) where the expression changes sign.
These critical points divide the real number line into intervals. List the intervals determined by the critical points: \((-\infty, 0)\), \((0, 1)\), \((1, 2)\), and \((2, \infty)\).
Choose a test point from each interval and substitute it into the expression \(-x(x - 1)(x - 2)\) to determine whether the expression is positive or negative on that interval.
Based on the inequality sign (≥ 0, > 0, ≤ 0, < 0), select the intervals where the expression satisfies the inequality. Remember to include or exclude the critical points depending on whether the inequality is strict or not.
Write the solution set in interval notation, combining the intervals where the inequality holds true, and include the critical points if the inequality is non-strict (≥ or ≤).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Polynomial Inequalities

Polynomial inequalities involve expressions where a polynomial is compared to zero using inequality symbols (>, ≥, <, ≤). Solving them requires finding the values of the variable that make the inequality true, often by analyzing the sign of the polynomial over different intervals.
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Critical Points and Sign Analysis

Critical points are the roots of the polynomial where the expression equals zero. These points divide the number line into intervals. By testing values in each interval, you determine whether the polynomial is positive or negative there, which helps identify the solution set for the inequality.
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Interval Notation

Interval notation is a concise way to represent sets of real numbers. It uses parentheses () for excluding endpoints and brackets [] for including them. This notation is essential for expressing the solution sets of inequalities clearly and precisely.
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Related Practice
Textbook Question

Use an end behavior diagram, as shown below, to describe the end behavior of the graph of each polynomial function. ƒ(x)=4x7-x5+x3-1

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Use one of the end behavior diagrams below, to describe the end behavior of the graph of each polynomial function.

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