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Learn how to solve and graph linear inequalities, including one-step, multi-step, and compound inequalities. Understand the symbols and rules involved in manipulating inequalities. Practice solving problems and interpreting graphs to master this essential algebraic concept.
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Algebra chapter 3 Solving and Graphing Linear Inequalities
Vocabulary • An equation is formed when an equal sign (=) is placed between two expressions creating a left and a right side of the equation • An equation that contains one or more variables is called an open sentence • When a variable in a single-variable equation is replaced by a number the resulting statement can be true or false • If the statement is true, the number is a solution of an equation • Substituting a number for a variable in an equation to see whether the resulting statement is true or false is called checking a possible solution
Inequalities • Another type of open sentence is called an inequality. • An inequality is formed when and inequality sign is placed between two expressions • A solution to an inequality are numbers that produce a true statement when substituted for the variable in the inequality
Inequality Symbols • Listed below are the 4 inequality symbols and their meaning < Less than ≤ Less than or equal to > Greater than ≥ Greater than or equal to Note: We will be working with inequalities throughout this course…and you are expected to know the difference between equalities and inequalities
Graphs of linear inequalities • Graph (1 variable) • The set of points on a number line that represents all solutions of the inequality
Writing linear inequalities • Bob hopes that his next math test grade will be higher than his current average. His first three test scores were 77, 83, and 86. • Why would an inequality be best in this case? • How can we come up with this inequality? • Graph!
Solving one-step linear inequalities • Equivalent Inequalities • Two or more inequalities with exactly the same solution • Manipulating Inequalities • All of the same rules apply to inequalities as equations* • When multiplying or dividing by a negative number, we have to switch the inequality! • Less than becomes greater than, etc.
Why do we have to change the sign? • Is there another way we can solve this?
Solving multi-step linear inequalities—3.2 Algebra chapter 3 • Solving and Graphing Linear Inequalities
Multi step inequalities • Treat inequalities just like you would normal, everyday equations* *change the sign when multiplying or dividing by a negative!!
Example • You plan to publish an online newsletter that reports the results of snow cross competitions. You do not want your monthly costs to exceed $2370. Your fixed monthly costs are $1200. You must also pay $130 per month to each article writer. How many writers can you afford to hire in a month?
o -5 -4 -3 o -5 -4 -3 ● -5 -4 -3 -5 -4 -3 Answer Now 1) Which graph represents the correct answer to > 1 ●
Answer Now 2) When solving > -10will the inequality switch? • Yes! • No! • I still don’t know!
Answer Now 3) When solving will the inequality switch? • Yes! • No! • I still don’t know!
Answer Now 4) Solve -8p ≥ -96 • p ≥ 12 • p ≥ -12 • p ≤ 12 • p ≤ -12
o -16 -15 -14 o -16 -15 -14 ● -16 -15 -14 -15 -15 -14 Answer Now 5) Solve 7v < -105 ●
Class work:p.343 #15-37 oddIf you do not finish in class, then it becomes homework!
Compound inequalities—3.6 Algebra chapter 3 • Solving and Graphing Linear Inequalities
Compound inequality • What does compound mean? • Compound fracture? • So…what’s a compound inequality? • An inequality consisting of two inequalities connected by an and or an or
Graphing Compound Inequalities • Graph the following:
Graphing Compound Inequalities • Graph the following:
Graphing Compound Inequalities • Graph the following: • All real numbers that are greater than or equal to -2 and less than 3
Solving Compound inequalities • Again….treat these like equations! • Whenever we do something to one side… …We do it to every side!
Solving Absolute-Value Equations and Inequalities—3.6 (Day 1)
Abs. Value • What is Absolute Value? • Distance from zero • What does that mean?
Abs. Value • So….an absolute value equation has how many solutions? • Is this always true?
Abs. Value • How do we apply this to equations? • Ex: