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Multiplying Integers. Rule #1: Integers can be multiplied in any order without affecting the product. What is the product of 3 x 2 or 3 groups of 2? What is the product of 2 x 3 or 2 groups of 3? Integers are similar: What is the product of 3 x (-2)? This is like saying 3 groups of -2
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Rule #1: Integers can be multiplied in any order without affecting the product • What is the product of 3 x 2 or 3 groups of 2? • What is the product of 2 x 3 or 2 groups of 3? • Integers are similar: • What is the product of 3 x (-2)? • This is like saying 3 groups of -2 • What about -3 x 2? There is no such thing as -3 groups of 2!
Rule #2: The product of a positive and a negative is negative. • In the previous question we couldn’t make -3 groups of 2. • BUT, we know that any positive number multiplied by any negative number will have a negative product. • So, -3 x 2 = -6, just like 3 x -2 = -6 • Think about a number line. You skip -3 two times.
Rule #3: The product of two positives or two negatives is positive • You already know that 3 x 2 = 6, but why does -3 x -2 = 6? • Look at this pattern: • 3 x (-2) = -6 • 2 x (-2) = -4 • 1 x (-2) = -2 • 0 x (-2) = 0 • -1 x (-1) = 2 • -2 x (-2) = 4 • - 3 x (-2) = ?
Rule #4: The distributive property applies to multiplication of integers just like whole numbers • The formula for the distributive property is a(b + c) = ab + ac • For example • 2 x 24 = 48 • 2(20) + 2(4) = 40 + 8 = 48 • 2 x -37 = ? • 2(-30) + 2(-7) = -60 + -14 = -74
Assignment and Quiz • Using these rules complete the assignment • If you have questions ask Mrs. George • When you have finished your assignment as Mrs. George for the answer sheet. • Correct your assignment. • If you scored 90% or higher you may get a computer to complete the quiz. • If you scored less than 90% you must do your correction. • Quiz: Go to www.thatquiz.org • At the bottom right corner type in the quiz code: DV9HRUPC • Click on your name…Go!