PreAlgebra III Chapter 5 Rationals: Patterns in Addition and Subtraction

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PreAlgebra III - Chapter 5Rationals Patterns
in Addition and Subtraction
Chapter 5-4 and 5-5 Adding and subtracting like
and unlike fractions

• Michelle OMalley
• League Academy of Communication Arts
• Greenville, South Carolina

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PreAlgebra III Standards for Chapter 5-4 and 5-5

• 8-1.1 Generate and solve complex, abstract
  problems that involve modeling physical, social,
  or mathematical phenomena.
• 8-1.7 Generalize connections among a variety of
  representational forms and real world situations.

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PreAlgebra III Chapter 5-4 and 5-5 Essential
Questions

• Why is it important to be able to compute with
  rational numbers in order to solve real life
  problems involving addition and subtraction?
• How do you add and subtract rational number
  problems involving fractions?

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Adding and Subtracting Fractions

• Only quantities that are alike can be added
  together
• Hundreds may be added to hundreds, tens to tens,
  ones to ones, tenths to tenths, fourths to
  fourths, etc. Thus only like fractions can be
  added.

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Adding and Subtracting Fractions

• The word denominator comes from the Latin word
  name.
• The denominator is the name of the fraction.
• The word numerator comes from the Latin word for
  number.
• The numerator tells how many of that quantity.

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Adding and Subtracting Like Fractions

• Like fractions are fractions that have the same
  denominators.
• Therefore, to add or subtract like fractions, one
  has only to add or subtract the numerators.
• Sums and differences should be expressed in
  simplest form.

5/6 1/6 3/6 (5 1 3) / 6 3/6 1/2
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Adding and Subtracting Unlike Fractions

• To add or subtract unlike fractions, however,
  they must be renamed so that they have the same
  denominator (name).
• The most efficient way to do this is to find the
  LCM (least common multiple) of the denominators
  to get the least common denominator (LCD).

5/6 (-3/4) 3/8 5/6 3/4 3/8
20/24 18/24 9/24 29/24 1 5/24
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Work Cited

• Alban, Yuria, et. al. Pre-Algebra An Integrated
  Transition to Algebra Geometry. New
  York Glencoe/McGraw-Hill, 2001.
• Greenville County Schools Math Curriculum Guide