Name: absolute value inequalities on a number line
Uploaded: 2025-11-26T05:44:25.000Z
Duration: 1 min 23 s
Channel: JoVE

La valeur absolue indique la distance entre un nombre et zéro sur la droite numérique, que le nombre soit positif ou négatif.Lorsque la valeur absolue d’une quantité est inférieure ou égale à une valeur donnée, la solution comprend tous les nombres compris entre les bornes négative et positive.Si la valeur absolue est supérieure ou égale à une valeur donnée, la solution inclut tous les nombres en dehors de ces limites.Ces solutions sont représentées sur une droite numérique à l’aide de segments ou de rayons, avec des cercles indiquant les extrémités incluses en raison de la partie égalité de l’inégalité.Envisagez de mesurer la vitesse du son à l’aide d’échos à une distance connue d’un mur. En fonction des fluctuations environnementales, la vitesse mesurée est d’environ 343 mètres par seconde, avec une variation de plus ou moins 2 mètres par seconde.Cette variation est modélisée à l’aide d’une inégalité de valeur absolue, qui fixe une limite à la distance entre la vitesse observée et la valeur attendue.Pour résoudre l’inégalité, il faut soustraire et ajouter la variation permise à la vitesse attendue pour obtenir la gamme complète de valeurs acceptables.

inégalités en valeur absolue

Absolute Value Inequalities

La valeur absolue est un outil math&#233;matique qui exprime la distance d&#8217;un nombre &#224; z&#233;ro sur la droite r&#233;elle, ind&#233;pendamment de son signe. Dans le cadre des in&#233;galit&#233;s, les expressions faisant intervenir la valeur absolue servent &#224; d&#233;finir un intervalle de valeurs admissibles ou des bornes pour une variable donn&#233;e. Ces in&#233;galit&#233;s sont fr&#233;quemment utilis&#233;es en mod&#233;lisation scientifique et en analyse de donn&#233;es, lorsque la variabilit&#233; &#224; l&#8217;int&#233;rieur ou au-del&#224; d&#8217;un certain seuil doit &#234;tre d&#233;crite avec pr&#233;cision.Une in&#233;galit&#233; en valeur absolue de la forme &#8739;x&#8739; &#8804; a, o&#249; a &#8805; 0, repr&#233;sente l&#8217;ensemble des valeurs de x comprises entre &#8722;a et a, incluses. Cette in&#233;galit&#233; peut &#234;tre r&#233;&#233;crite sous la forme d&#8217;une in&#233;galit&#233; double :<figure class='image image-style-align-center image_resized' style='display:table;margin-left:auto;margin-right:auto;width:50%;'><img style='aspect-ratio:1920/120;' src='https://cloudfront.jove.com/files/ftp_upload/40036/40036_Equation_1_2__editor_40036.svg' alt='40036_Equation_1_2_.svg' /></figure>Sur la droite r&#233;elle, cet intervalle est illustr&#233; par un segment reliant les points &#8722;a et a, souvent accompagn&#233; de points pleins pour indiquer que les bornes appartiennent &#224; la solution.&#192; l&#8217;inverse, une in&#233;galit&#233; de la forme &#8739;x&#8739; &#8805; a indique que x se situe &#224; une distance au moins &#233;gale &#224; a de z&#233;ro. L&#8217;ensemble des solutions se compose alors de deux intervalles distincts :<figure class='image image-style-align-center image_resized' style='display:table;margin-left:auto;margin-right:auto;width:50%;'><img style='aspect-ratio:1920/120;' src='https://cloudfront.jove.com/files/ftp_upload/40036/40036_Equation_2_2__editor_40036.svg' alt='40036_Equation_2_2_.svg' /></figure>Graphiquement, ces intervalles sont repr&#233;sent&#233;s par deux demi-droites partant de &#8722;a et de a, s&#8217;&#233;tendant vers l&#8217;ext&#233;rieur, avec des points pleins lorsque les bornes sont incluses.Prenons l&#8217;exemple d&#8217;une r&#233;action chimique qui atteint ses conditions optimales &#224; 80 &#176;C. Pour assurer la s&#233;curit&#233; et le rendement en produit, la temp&#233;rature doit rester dans un &#233;cart maximal de 2,5 &#176;C autour de cette valeur. Cette contrainte s&#8217;exprime par l&#8217;in&#233;galit&#233;&#160;:<figure class='image image-style-align-center image_resized' style='display:table;margin-left:auto;margin-right:auto;width:50%;'><img style='aspect-ratio:1920/120;' src='https://cloudfront.jove.com/files/ftp_upload/40036/40036_Equation_3_2__editor_40036.svg' alt='40036_Equation_3_2_.svg' /></figure>Cette relation signifie que la temp&#233;rature x peut diff&#233;rer d&#8217;au plus 2,5 &#176;C de la valeur id&#233;ale. En r&#233;solvant cette in&#233;galit&#233;, on obtient :<figure class='image image-style-align-center image_resized' style='display:table;margin-left:auto;margin-right:auto;width:50%;'><img style='aspect-ratio:1920/120;' src='https://cloudfront.jove.com/files/ftp_upload/40036/40036_Equation_4_2__editor_40036.svg' alt='40036_Equation_4_2_.svg' /></figure>Ainsi, toute temp&#233;rature comprise dans cet intervalle garantit le maintien de conditions de r&#233;action optimales.

Inégalités en valeur absolue

La valeur absolue est un outil math&#233;matique qui exprime la distance d&#8217;un nombre &#224; z&#233;ro sur la droite r&#233;elle, ind&#233;pendamment ...

Education

Enseignement

JoVE Core

Math Fundamentals

Fondamentaux des mathématiques

Unit

Unité

Foundations of Mathematics

Fondements des mathématiques

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

absolute value inequalities on a number line

Absolute value inequalities show how far a number can be from zero or from a target value. Absolute value means distance on the number line, so the sign of the number does not matter. In inequalities, this distance helps define a valid range of values for a variable.

An inequality of the form |x| ≤ a, where a ≥ 0, includes every x between −a and a. This can also be written as a compound inequality. On a number line, the solution is shown as a solid segment from −a to a with closed circles at the endpoints, because the endpoints are part of the answer.

An inequality of the form |x| ≥ a means x is at least a units away from zero. Its solution has two separate intervals, one on each side of zero. These are usually drawn as rays extending outward from the endpoints, and closed circles are used when the endpoints are included.

These inequalities are useful in scientific modeling and data interpretation, where values must stay within a set limit or beyond a boundary. A chemical reaction that works best at 80°C can be used as an example. If the temperature must stay within 2.5°C of 80°C, the condition can be written as an absolute value inequality.

That inequality shows that the temperature x may vary only a small amount from the ideal value. Solving it gives an interval of acceptable temperatures. Any temperature in that interval keeps the reaction in its optimal range.

Absolute Value Inequalities on a Number Line

absolute-value-inequalities-on-a-number-line

real number system

Number Types on the Real Line

The real number system brings together the number types used for counting, measuring, and comparing quantities. It includes natural numbers, integers, rational numbers, and irrational numbers. Each set adds new kinds of numbers to the same system. Natural numbers are the basic counting numbers: 1, 2, 3, and so on. Integers extend that set by adding zero and negative whole numbers, such as ..., -3, -2, -1, 0, 1, 2, .... Rational numbers are numbers that can be written as a ratio of two...

real number operations

Real Numbers on the Number Line

Real numbers are the values that can be placed on a continuous number line. The system grew from counting numbers used for enumeration. It later expanded to include zero, which shows the absence of quantity, and negative numbers, which are opposites of counting numbers. The real number system also includes fractions and decimals that represent parts of a whole or equal divisions. When written in decimal form, these numbers may end or repeat in a regular pattern. Together, these values describe...

exponents

Exponent Rules and Scientific Notation

Exponents show repeated multiplication in a short form. They are important in algebra and in many other math topics, including scientific computation, scaling laws, and dimensional analysis. For a nonzero real number a and an integer n, a^n means a multiplied by itself n times. Exponent rules help simplify expressions with powers. These properties make it easier to work with exponential expressions in both symbolic and numerical form. They also support common calculations that use exponents in...

radicals

Simplifying Radicals

Radicals show the root of a number and the exponent needed to get that value. A radical expression has two main parts. The radicand is the number inside the root symbol, and the index tells which root to take. The notation n√a means the principal nth root of a. The index changes the type of root. When n equals 2, the expression is a square root. When n equals 3, it is a cube root. The sign of the radicand also matters. If the index is even, a negative radicand does not give a real result. If...

algebraic expressions

Simplifying Algebraic Expressions

Algebraic expressions use variables, constants, and operations to show mathematical relationships. They help describe patterns and solve problems across many areas of mathematics. Knowing the parts of an expression makes it easier to simplify and work with it correctly. Each algebraic expression has separate pieces that work together. A coefficient is the number attached to a variable, and an exponent shows repeated multiplication. Some expressions have a single part, while others include...

rational expressions

Working with Rational Expression Domains

Rational expressions are algebraic fractions with polynomials in the numerator and denominator. They follow the same basic rules as numerical fractions, but variables make them more delicate to work with. A key step is finding values that make the expression undefined, usually because of division by zero or an undefined radical. To determine the domain, start by identifying the values excluded from the denominator. The domain includes all real numbers except those that make the denominator...

linear equations

Solving Linear Equations

Linear equations are a basic algebra tool for modeling constant rates and everyday relationships. They use constants and a single variable, and each term is either a constant or a product of a constant and that variable. When graphed on a Cartesian coordinate plane, they form a straight line that shows a constant rate of change between two quantities. A linear equation in one variable often has the form ax + b = c, where a, b, and c are constants and x is the variable. Solving the equation...

quadratic equations

Solving Quadratics by Factoring and Formula

Quadratic equations are algebraic equations with a variable squared, a first-power term, and a constant term. They are set equal to zero. In high school math, they often help model area, motion, and optimization problems. The general form of a quadratic equation uses real numbers a, b, and c, with a not equal to zero. The nonzero a value keeps the squared term in the equation. One common way to solve a quadratic is to rewrite it as a product of two linear expressions. In factored form, the...

complex numbers

Complex Numbers in Solving Equations

Complex numbers extend the real number system so equations with negative square roots can still be solved. The real numbers cannot represent the square root of a negative number. That limits some quadratic equations, especially those with negative discriminants. To solve this problem, mathematicians introduced the imaginary unit i, where i = √(-1). A complex number is written as x + yi, where x and y are real numbers. In this form, x is the real part and y is the imaginary part. The key rule...

quadratic equations in the complex number system

quadratic-equations-in-the-complex-number-system

Complex Roots of Quadratic Equations

Quadratic equations can have real or complex roots, depending on the discriminant. For an equation in the form ax² + bx + c = 0, the coefficients a, b, and c are the numbers that multiply x², x, and the constant term. The discriminant, b² − 4ac, tells us what kind of solutions to expect. When the discriminant is negative, the equation has no real number solutions. In that case, complex numbers provide a way to continue solving the problem. The imaginary unit i is defined by i = √−1, so a...

radical equations

Solving Radical Equations with Checks

Radical equations are equations with a variable inside a radical, most often a square root or cube root. These equations appear in science, engineering, and real-world measurement problems that involve nonlinear relationships. Solving them starts by isolating the radical expression. Then the radical is removed by raising both sides to the power that matches the radical’s index. This process can create extraneous solutions, which are values that work in the transformed equation but not in the...

inequalities

Solving Inequalities and Interval Notation

Inequalities show how two values compare when they are not equal. They use symbols such as , ≤, and ≥. These statements often describe a range of possible answers instead of one exact value. Interval notation is a shorter way to write these solution sets. An open interval, written as (a, b), leaves out the endpoints. A closed interval, written as [a, b], includes both endpoints. Half-open intervals, such as (a, b] and [a, b), include only one endpoint. Intervals can also extend forever in one...

absolute value inequalities

Absolute value inequalities show how far a number can be from zero or from a target value. Absolute value means distance on the number line, so the sign of the number does not matter. In inequalities, this distance helps define a valid range of values for a variable. An inequality of the form |x| ≤ a, where a ≥ 0, includes every x between −a and a. This can also be written as a compound inequality. On a number line, the solution is shown as a solid segment from −a to a with closed circles at...

mathematical modeling: problem solving

Mathematical Modeling for Loan Payments

Mathematical modeling turns a real-life situation into an equation that can be solved. It starts with defining the problem, choosing measurable quantities, and assigning variables to them. Then a matching model is selected and the equation is solved for the unknown value. This process is especially useful in finance, where models help evaluate investments, loans, and repayment plans. One common example is finding the fixed monthly payment on a loan. That calculation uses the standard annuity...

key terms and concepts

Learn how absolute value inequalities show distance from zero, form compound inequalities, and appear on a number line with a science-based temperature example.

Absolute Value Inequalities on a Number Line | JoVE K12

The JoVE Math Fundamentals collection is designed to build a deep and comprehensive understanding of essential mathematics. Covering the foundations of algebra, geometry, trigonometry, and analytic reasoning, this course establishes a strong base for future studies. The collection connects core mathematical concepts with real-world practice, equipping learners to solve complex problems, master problem-solving skills, and apply abstract ideas.

math fundamentals

Absolute Value Inequalities on a Number Line

Description

Transcript

Tags