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Learn about absolute value equations, solving strategies, and examples with absolute values indicated by vertical bars. Practice evaluating expressions and solving equations with absolute values in this comprehensive lesson.
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Definition of Absolute Value • “Absolute value” means “distance away from zero” on a number line • Distance is always positive or zero • Absolute value is indicated by placing vertical parallel bars on either side of a number or expression Examples: The distance away from zero of -3 is shown as: The distance away from zero of 3 is shown as: The distance away from zero of u is shown as: = u
Absolute Value Equation • An equation that has a variable contained within absolute value symbols • Examples: | 2x – 3 | + 6 = 11 | x – 8 | – | 7x + 4 | = 0 | 3x | + 4 = 0
Solving Absolute Value Equations • Isolate one absolute value that contains an algebraic expression, | u | • If the other side is negative there is no solution (distance can’t be negative) • If the other side is zero, then write: • u = 0 and Solve • If the other side is “positive n”, then write: • u = n OR u = - n and Solve • If the other sideis another absolute value expression, | v |, then write: • u = v OR u = - v and Solve
Lesson 4 Contents Example 1Evaluate an Expression with Absolute Value Example 2Solve an Absolute Value Equation Example 3No Solution Example 4One Solution
Evaluate Replace x with 4. Simplify –2(4) first. Subtract 8 from 6. Add. Example 4-1a Answer: The value is 4.7.
Evaluate Example 4-1b Answer: –13.7
Solve Check your solutions. Case 1 Case 2 or Check: Answer: The solutions are5 or –11. Thus, the solution set is Example 4-2a
Solve Check your solutions. Answer: Example 4-2b
Solve Original equation Subtract 5 from each side. Example 4-3a This sentence is never true. Answer: The solution set is .
Solve Example 4-3b Answer:
Solve Check your solutions. Case 1 Case 2 or There appear to be two solutions, 11 or Example 4-4a
Check: Answer: Since , the only solution is 11. The solution set is {11}. Example 4-4b
Solve Example 4-4c Answer: {6}
Homework • Pages 30 – 31 #’s 18 – 26, 29 – 40 Due Tomorrow (9/9/09)