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Absolute value (sometimes called modulus or magnitude) is how far a number, term, polynomial, or expression is from zero, regardless of whether it is positive or negative. For example: <math>4</math> and <math>-4</math> are the same distance from <math>0</math>, so they both have an absolute value of <math>4</math>.<br><br>
<img width="500" alt="Absolute value" src="https://user-images.githubusercontent.com/56831176/146247143-c8db661d-83ab-457f-9087-e9bc5cfa4ba3.png"><br>
Absolute value is represented by two bars, one of each side of the number, term, polynomial, or expression. For example, the absolute value of <math>-4</math> would be written as <math>|-4|</math><br><br>
<h3>Properties of absolute values</h3>
<ul>
<li>Non-negativity: <math>|x|≥0</math><br>
Absolute value is always non-negative, meaning it <b>always</b> yields zero or a positive.</li><br>
<li><math>|x|=\sqrt{x^2}</math>: Squaring a number makes it positive (or zero if the number is zero), and by taking the square root of a squared number we get a positive solution (or zero if the number is zero). This only works when <math>x</math> is a real number.</li><br>
<li>Multiplicativity: <math>|x\cdot y|=|x|\cdot|y|</math><br>
The absolute value of a product of two numbers equals the product of the absolute value of each number.</li><br>
<li>Subadditivity: <math>|x+y|≤|x|+|y|</math><br>
The absolute value of the sum of two real numbers is less than or equal to the sum of the absolute values of the two numbers.</li><br>
<li><math>|x|=y → x=\pm y</math> or <math>|x|=\pm x</math>: If the absolute value of <math>x</math> equals <math>y</math> then <math>x</math> equals plus or minus <math>y</math>. This rule is used for solving most absolute value questions.</li>
</ul>
<br><br>
<h3>Absolute value equations</h3>
Absolute value equations are equations in which the variable is within an absolute value operator.<br>
For example: <math>|x-4|=10</math><br>
Because the value of <math>x-4</math> can be <math>10</math> or <math>-10</math>, both of which have an absolute value of <math>10</math>, we need to consider both cases: <math>x-4=10</math> and <math>x-4=-10</math>. This can also be written as <math>x-4=\pm10</math>.<br><br>
So, <math>|x-4|=10</math> has two solutions:<br>
<math>x-4=10</math> → <math>x=14</math><br>
<math>x-4=-10</math> → <math>x=-6</math><br><br>
Because absolute values are always non-negative, it is possible to have equations with no solutions.<br>
For example: <math>|x - 5|=-9</math><br><br>
Absolute Value Equations and Inequalities are solved and explained step by step by the Tiger Algebra Absolute Value module.
<br><br>
Les équations et les inégalités de valeur absolue sont résolues et expliquées étape par étape par le module Valeur absolue Tiger Algebra.