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Ch. 3 - Polynomial and Rational Functions
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Non è quello che usi tu?Cambia libro di testo
Capitolo 4, Problema 71

In Exercises 71–72, use the graph of the polynomial function to solve each inequality.


2x3+11x2≥7x+62x^3 + 11x^2 ≥ 7x + 6
Graph of the function f(x) = 2x^3 + 11x^2 - 7x - 6 with labeled axes.

Guida verificata passo dopo passo
1
Rewrite the given inequality \(2x^3 + 11x^2 \geq 7x + 6\) by bringing all terms to one side to set the inequality to zero: \(2x^3 + 11x^2 - 7x - 6 \geq 0\).
Recognize that the expression on the left side is the polynomial function \(f(x) = 2x^3 + 11x^2 - 7x - 6\) whose graph is provided.
Identify the x-values where \(f(x) = 0\) by looking at the points where the graph crosses the x-axis. These are the roots of the polynomial and critical points for the inequality.
Determine the intervals on the x-axis where the graph of \(f(x)\) is above or on the x-axis (i.e., where \(f(x) \geq 0\)). These intervals satisfy the inequality.
Express the solution set as the union of intervals where \(f(x) \geq 0\), based on the x-intercepts and the behavior of the graph between these points.

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Polynomial Functions and Their Graphs

A polynomial function is an expression involving variables raised to whole-number exponents and their coefficients. The graph of a polynomial function shows its behavior, including where it crosses the x-axis (roots) and its general shape. Understanding the graph helps in visualizing solutions to inequalities involving the polynomial.
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Solving Polynomial Inequalities Using Graphs

To solve inequalities like f(x) ≥ 0 using a graph, identify where the graph lies above or on the x-axis. The x-values corresponding to these regions satisfy the inequality. The points where the graph touches or crosses the x-axis are critical points that divide the number line into intervals to test.
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Finding Roots of Polynomial Functions

Roots or zeros of a polynomial are the x-values where the function equals zero, i.e., where the graph crosses the x-axis. These roots are essential for solving inequalities because they mark boundaries between positive and negative values of the function. They can be found algebraically or estimated from the graph.
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