Adding Rational Numbers

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2.1

• Adding Rational Numbers

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2.1 Adding Rational s

• Goals / I can
• Add rational numbers using models and rules
• Apply addition

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2.1 Adding Rational s

• What is your identity?
• What is the inverse of something?

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2.1 Adding Rational s

• PROPERTY Identity Property of Addition
• For all real numbers, n 0 n and 0 n n
• PROPERTY Inverse Property of Addition
• For all real numbers, n (-n) 0
• additive inverse

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2.1 Adding Rational s

• RULE Adding Numbers
• When adding number with the same sign, the sum
  has the same sign.
• When adding number with different signs, subtract
  the numbers and keep the sign from the larger
  absolute value.

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2.1 Adding Rational s

• Example
• 12 (-23)
• -55 (-32)

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2.1 Adding Rational s

• Example
• The water level in a lake rose 6 inches and then
  fell 11 inches. Write a statement to show the
  total level change.

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2.1 Adding Rational s

• How would you read the expression n?
• It should be read as the opposite of n, because
  what happens if n is negative.

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2.1 Adding Rational s

• Evaluate
• -x 23 if x -14
• 42 (-y) if y 17

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2.1 Adding Rational s

• Matrices
• A Matrix is a collection of number in rows and
  columns.
• Each number is called an Element.
• A matrix is defined by the number of rows by
  columns.

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2.1 Adding Rational s

• is a 3 x 4 matrix. 3 rows x 4 columns.

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2.1 Adding Rational s

• Example 6