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Ch. 3 - Polynomial and Rational Functions
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514당신이 사용하는 게 아니라요?교과서 변경
4장, 문제 20

Solve each polynomial inequality in Exercises 1–42 and graph the solution set on a real number line. Express each solution set in interval notation. x2+2x<0x^2+2x<0

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Start by writing the inequality: \(x^2 + 2x < 0\).
Factor the left-hand side expression: \(x^2 + 2x = x(x + 2)\).
Set the product less than zero: \(x(x + 2) < 0\). This means the product of two factors is negative.
Determine the critical points by setting each factor equal to zero: \(x = 0\) and \(x + 2 = 0 \Rightarrow x = -2\). These points divide the number line into intervals.
Test values from each interval \((-\infty, -2)\), \((-2, 0)\), and \((0, \infty)\) in the inequality \(x(x + 2) < 0\) to find where the product is negative, then express the solution set in interval notation.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Solving Polynomial Inequalities

Solving polynomial inequalities involves finding the values of the variable that make the inequality true. This typically requires factoring the polynomial, determining critical points where the expression equals zero, and testing intervals between these points to see where the inequality holds.
추천 영상:
06:07
Linear Inequalities

Factoring Quadratic Expressions

Factoring quadratic expressions means rewriting the quadratic as a product of two binomials. For example, x² + 2x can be factored as x(x + 2). Factoring helps identify the roots or zeros of the polynomial, which are essential for analyzing the inequality.
추천 영상:
06:08
Solving Quadratic Equations by Factoring

Interval Notation and Number Line Graphing

Interval notation is a way to represent solution sets using intervals, such as (a, b) or [a, b), indicating which numbers satisfy the inequality. Graphing on a number line visually shows these intervals, helping to understand where the polynomial is positive or negative.
추천 영상:
05:18
Interval Notation