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Ch. 3 - Polynomial and Rational Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
4장, 문제 14

Solve each quadratic inequality. Give the solution set in interval notation. (x-4)(x + √2) < 0

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Start by identifying the critical points of the inequality by setting each factor equal to zero: solve \(x - 4 = 0\) and \(x + \sqrt{2} = 0\).
The solutions to these equations are the critical points \(x = 4\) and \(x = -\sqrt{2}\). These points divide the number line into three intervals: \(( -\infty, -\sqrt{2} )\), \(( -\sqrt{2}, 4 )\), and \(( 4, \infty )\).
Choose a test point from each interval and substitute it into the expression \((x - 4)(x + \sqrt{2})\) to determine the sign (positive or negative) of the product in that interval.
Since the inequality is \((x - 4)(x + \sqrt{2}) < 0\), select the intervals where the product is negative based on your test points.
Express the solution set as the union of intervals where the product is negative, using interval notation and excluding the critical points since the inequality is strict (less than zero, not less than or equal to zero).

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주요 개념

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

Quadratic Inequalities

A quadratic inequality involves a quadratic expression set to be greater than or less than zero. Solving it requires finding the values of the variable that make the inequality true, often by analyzing the sign of the quadratic expression over different intervals.
추천 영상:
가이드 코스
3:21
Nonlinear Inequalities

Factoring Quadratic Expressions

Factoring breaks down a quadratic expression into the product of two binomials. This helps identify the roots or zeros of the quadratic, which are critical points that divide the number line into intervals for testing the inequality.
추천 영상:
06:08
Solving Quadratic Equations by Factoring

Interval Notation and Sign Analysis

Interval notation expresses the solution set as ranges of values. After finding the roots, sign analysis determines where the product of factors is positive or negative by testing points in each interval, allowing the correct intervals to be selected for the inequality.
추천 영상:
05:18
Interval Notation