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MTH 11203 Algebra. Multiplication and division of Real Numbers CHAPTER 1 Section 8. Multiply Numbers. The Sign of the Product of Two Real Numbers Rule 1: The product of two numbers with like signs is a positive number (-) · (-) = + (+) · (+) = +
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MTH 11203Algebra Multiplication and division of Real Numbers CHAPTER 1 Section 8
Multiply Numbers • The Sign of the Product of Two Real Numbers • Rule 1: The product of two numbers with like signs is a positive number (-) · (-) = + (+) · (+) = + • Rule 2: The product of two numbers with unlike signs is a negative number (+) · (-) = - (-) · (+) = - • Multiplication and division of decimals are covered in appendix A.
Multiply Numbers • Example # 18: -4(2) = -8 neg. because different signs • Example # 20: 6(-2) = -12 neg. because different signs • Example # 21: (-8)(-10) = 80 pos. because same signs • Example: (6)(-9) = -54 neg. because different signs
Multiply Numbers • Example: (-8)(-4) = 32 pos. because same signs • Example: (0)(-8) = 0 0 is never pos. or neg. • Example: (-4)(-6) = 24 pos. because same signs • Careful not to confuse subtraction with multiplication Example -4 – 5 (-4)(-5) -4 + (-5) 20 -9
Multiply Numbers • Example • Example • Remember that negatives can be written different ways
Multiply Numbers • Multiplication of more that one number in a given problem: • Helpful hint: • Even number of negatives will equal a positive result • Odd number of negatives will equal a negative result • Example # 90 pg 67: 4(-2)(-1)(-5) Odd negatives equals negative results (-8)(-1)(-5) (8)(-5) -40
Multiply Numbers • Example : (-3)(2)(-1)(-2)(-4) Even negatives equals (-6)(-1)(-2)(-4) positive results (6)(-2)(-4) (-12)(-4) 48 • Example : (-3)(4)(-9)(-3) Odd negatives equals (-12)(-9)(-3) Negative results (108)(-3) -324
Multiply Numbers • Example : (-2)(4)(-1)(-3)(-5) Even negatives equals (-8)(-1)(-3)(-5) positive results (8)(-3)(-5) (-24)(-5) 120
Divide Numbers • The Sign of the Quotient of Two Real Numbers • Rule 1: The Quotient of two numbers with like signs is a positive number (-) ÷ (-) = + (+) ÷ (+) = + • Rule 2: The Quotient of two numbers with unlike signs is a negative number (+) ÷ (-) = - (-) ÷ (+) = -
Divide Numbers • Example # 52 pg 66: Example # 50 pg 66: 25 ÷ 5 or • Example # 54 pg 66: Example # 53 pg 66:
Divide Numbers • Example # 50 pg 66: -12.37 ÷ 3.2 or
Divide Numbers • Example: Example : • Example:
Divide Numbers • Example # 80 pg 66: • Remember: • We should write all fractions with the negative in front , this will be the class standard
Divide Numbers • Example: • Example:
Summary of Operation of Real Numbers • Page 64 Summarizes of Operation of Real Numbers • Addition • Subtraction • Multiplication • Division • This is a good chart to use as a study guide for a test.
Evaluate Divisions Involving 0 • Zero Divided by a Nonzero Number • If a represents any real number except 0, then • Examples:
Evaluate Divisions Involving 0 • Division by Zero • If a represents any real number except 0, then • Examples:
HOMEWORK 1.8 • Page 66 - 67 17, 19, 26, 29, 33, 35, 43, 45, 51, 62, 63, 67, 95