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Distances on Number Lines An Application of Absolute Value. |2x + 3| = -7. What’s wrong? Absolute value can not be equal to a negative number. Therefore, there are no solutions. |2x + 3| = -7. Distance of -7?. 2x+3 0 2x+3. Distance can never be negative.
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|2x + 3| = -7 • What’s wrong? • Absolute value can not be equal to a negative number. • Therefore, there are no solutions.
|2x + 3| = -7 • Distance of -7? 2x+3 0 2x+3
Distance can never be negative • If the isolated absolute value is equal to a negative, the solution(s) will be extraneous.
a + b m = 2 Midpoint • The average of the two coordinates.
Midpoint • Find the midpoint between 4 and 10. 4 5 6 7 8 9 10
Midpoint • Find the midpoint between -3 and 17. • Midpoint = 7
Midpoint • Find the midpoint between -3 and -10. • Midpoint = -6.5
Distance • If d is the distance between points a and b, then d = |a – b| = |b – a|. • It doesn’t matter which direction you subtract.
Distance • What is the distance between • 4 and 7 |4 – 7| = 3 • 25 and 34 |25 – 34| = 9 • -2 and 6 |-2 – 6| = 8 Distance is the absolute value of the difference.
Distance • Find the distance between 4 and 10. • The distance is 6 units. 4 5 6 7 8 9 10
Distance • Find the distance between -5 and 9. • Distance = 14
Distance • Find the distance between -3 and -21. • Distance = 18
Distance • Find the distance between 27 and 71. • Distance = 44
Translating to Equations • The distance from 4 to a number is 2. • There are 2 units between some number and 8. • A number’s distance from 0 is 6.
Translating to Equations • The distance between a number x and -6 is 5. • x and -3 are 8 units apart.
Translating • The distance between x and 5 is 4. • |5 – 4| = x • |x – 5| = 4 • |x – 5| = 1 • None of these
Translating • The distance between 2 and a number is 6. • |6 – 2| = x • |x – 6| = 2 • |x – 2| = 6 • None of these
Translating • 5 is 9 units from some number. • |5 – 9| = x • |x – 9| = 5 • |x – 5| = 9 • None of these
Section 2.4 • pp. 56-57