Homework # 6 – Word Problems pg 79 #57 In golf, your score on a hole is the number of strokes above or below an expected number of strokes needed to hit a ball into a hole. As shown in the table, each score has a name. When you compare two scores, the lesser score is the better score. Name Double Eagle Eagle Birdie Par Bogey Double Score -3 -2 -1 1 2 a) Compare: For three holes, you score an eagle, a double bogey, and a birdie. Your friend scores a double eagle, a bogey, a bogey, and a par. Who has the better total score? b) Explain: Your friend scores a double eagle and an eagle for the next two holes. Is it possible for you to have a better score on all five holes after your next two holes? Explain your reasoning.

Properties of Multiplication Section 2.4 – Multiply Real Numbers Properties of Multiplication Property Definition Algebra Example Commutative The order in which you multiply two numbers does not change the product. a * b = b * a 4 * (-3) = -3 * 4 Associative The way you group three numbers in a product does not change the product. (a * b) * c = a * (b * c) (-3 * 2) * 4 = -3 * (2 * 4) Identity The product of a number and 1 is that number. a * 1 = 1 * a = a 2 * 1 = 2 Zero The product of a number and 0 is 0. a * 0 = 0 * a = 0 -5 * 0 = 0 Negative 1 The product of a number and -1 is the opposite of the number. a * (-1) = -1 * a = - a - 2 * (-1) = 2 Multiplicative Identity – is the number 1.

Example # 1 Find the product: -2 * (c * (-0.5)). Justify your steps. Section 2.4 – Multiply Real Numbers Example # 1 Find the product: -2 * (c * (-0.5)). Justify your steps. -2 * (c * (-0.5)) = (c * (-0.5)) * (-2) Commutative Property = c * (-0.5 * (-2)) Associative Property = c * 1 Multiplication Property = c Identity Property

Section 2.4 – Multiply Real Numbers Example # 2 From 1900 to 1940, a 250-foot wide beach on the Atlantic coast was eroding at a rate of about -0.02 feet per year. From 1940 to 2000, it was eroding at a rate of about -0.12 feet per year. Approximate the width of the beach in 2000. Write a verbal model. New Width of the Beach = (feet) Original Width of Beach (feet) Average rate + of erosion (feet per year) Time * passed (years) Calculate the Width of the Beach in 1940 (New width of the Beach). Use the elevation in 1900 as the Original Elevation of the Beach. The time span is 1940 – 1900 = 40 years. Substitute Values into the verbal model New width of the Beach = 250 + (-0.02)*(40) Multiply -0.02 and 40 Width of Beach in 1940 = 250 + (-0.8) Add 250 and -0.8 Width of Beach in 1940 = 249.2 Did we answer the Question?

Section 2.4 – Multiply Real Numbers Example # 2 (con’t) From 1900 to 1940, a 250-foot wide beach on the Atlantic coast was eroding at a rate of about -0.02 feet per year. From 1940 to 2000, it was eroding at a rate of about -0.12 feet per year. Approximate the width of the beach in 2000. Calculate the Width of the Beach in 2000. (Final width of the Beach). Use the elevation in 1940 as the New Original Elevation of the Beach. The time span is 2000 – 1940 = 60 years. Substitute Values into the verbal model Final Width of the Beach = 249.2 + (-0.12)*(60) Multiply -0.12 and 60 Width of Beach in 2000 = 249.2 + (-7.2) Add 249.2 and -7.2 Width of Beach in 2000 = 242 Approximate Width of the Beach in 2000 is 242 feet

Section 2.4 Homework # 7 pg 91 # 17 – 43 odd; # 44, # 51