26 Chapter 1 Real Numbers and Algebraic Expressions 6c. From 2004 to 2010, the number of active users (in millions) of Facebook can be modeled by the expression 4.3x4 - 32.5x3 + 80.9x2 - 55.5x + 2.2 where x is the number of years after 2004. According to the model, how many active users were there in 2009? (Source: http://www.facebook.com/press/ info.php?timeline) Solution 6c. The variable x represents the number of years after 2004. Since 2009 − 2004 = 5, we replace x with 5 to obtain the requested information. 4.3x4 - 32.5x3 + 80.9x2 - 55.5x + 2.2 Begin with given model. = 4.3(5)4 - 32.5(5)3 + 80.9(5)2 - 55.5(5) + 2.2 Replace x with 5. = 4.3(625) - 32.5(125) + 80.9(25) - 55.5(5) + 2.2 Simplify each exponent. = 2687.5 - 4062.5 + 2022.5 - 277.5 + 2.2 Multiply from left to right. = 372.2 Add or subtract from left to right. So, in 2009, there were about 372.2 million active users of Facebook. 6d. Busch Stadium in St. Louis, Missouri, is home to the St. Louis Cardinals. The stadium is almost a perfect circle with a diameter of 800 ft. The distance around a circle is called its circumference. The circumference is represented by the expression πd, where d is the circle’s diameter. Find the distance around Busch Stadium. Approximate the answer to two decimal places. (Source: http://www .baseball-statistics.com/Ballparks/StL/index.htm) Solution 6d. The stadium’s diameter is 800 ft. C = πd State the circumference formula. C = π(800) Replace d with 800. C ≈ 2513.27 Multiply and round to two decimal places. The distance around the stadium is approximately 2513.27 ft. That is nearly half of a mile! Student Check 6 Solve each problem. a. What is the net worth of the Bowden family if their assets are $300,000 and their liabilities are $450,000? b. The chart shows the closing price of Target’s stock for a week in June 2011. (Source: http://finance.yahoo.com) Date Closing Price Daily Change in Price 6/06/2011 $47.36 n/a 6/07/2011 $47.06 6/08/2011 $46.86 6/09/2011 $47.16 6/10/2011 $46.70 i. Complete the chart to show how the price of the stock changed from the previous day to the next. ii. After completing the chart, find the average daily change in price. c. From January 2002 to January 2011, the average retail price (in dollars per gal) of regular gas in California can be approximated by the expression 0.0012x5 - 0.0265x4 + 0.1862x3 - 0.4490x2 + 0.3783x + 1.5576, where x is the number
hendricks_intermediate_algebra_1e_ch1_3
To see the actual publication please follow the link above