{"id":793,"date":"2016-10-19T04:27:28","date_gmt":"2016-10-19T04:27:28","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/waymakercollegealgebra\/?post_type=chapter&p=793"},"modified":"2017-04-04T18:55:33","modified_gmt":"2017-04-04T18:55:33","slug":"why-it-maters-quadratic-functions","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/ivytech-wmopen-collegealgebra\/chapter\/why-it-maters-quadratic-functions\/","title":{"raw":"Why It Matters: Quadratic Functions","rendered":"Why It Matters: Quadratic Functions"},"content":{"raw":"

Why study quadratic functions?<\/h2>\r\n\"PersonAn arrow is shot into the air. \u00a0How high will it go? \u00a0How far away will it land? \u00a0It turns out that you can answer these and related questions with just a little knowledge of quadratic functions. \u00a0In fact quadratic functions can be used to track to the position of any object that has been thrown, shot, or launched near the surface of the Earth. \u00a0As long as wind resistance does not play a huge role and the distances are not too great, you can use a quadratic function to model the flight path.\r\n\r\nFor example, suppose an archer fires an arrow from a height of 2 meters above sea level on a calm day. \u00a0While the arrow is in the air, someone else tracks and records its height precisely at each second. The following table shows the arrow\u2019s height (meters) versus time (seconds).\r\n\r\n \r\n\r\n\r\n\r\n\r\n\r\n\r\n
Time ([latex]t[\/latex])<\/td>\r\nHeight ([latex]h[\/latex])<\/td>\r\n<\/tr>\r\n
0 sec.<\/td>\r\n2 m<\/td>\r\n<\/tr>\r\n
1 sec.<\/td>\r\n16.7m<\/td>\r\n<\/tr>\r\n
2 sec.<\/td>\r\n21.6 m<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n \r\n\r\nLet\u2019s plot the data on a coordinate plane. \u00a0Notice the up-and-down shape?\r\n\"Downward\r\n\r\nLet\u2019s plot the data on a coordinate plane. \u00a0Notice the up-and-down shape? As Isaac Newton would say, what goes up must come down. \u00a0The smooth arc, first rising and then falling, is a tell-tale clue that there is a quadratic function lurking in the data. \u00a0The curve that best fits this situation is a parabola, which is what we call the graph of a quadratic function. \u00a0With a little more work, you can find the equation of this function:\r\n

[latex]h(t)=-4.9t^2+19.6t+2[\/latex]<\/p>\r\n \r\n\r\nIn the above equation, [latex]t[\/latex] represents time in seconds, and [latex]h[\/latex] represents height in meters. This is an example of a quadratic function. By analyzing the function, you can figure out precisely how high the arrow will go and when it will hit the ground.\r\n\r\nIn this module you\u2019ll learn how to graph and analyze quadratic functions and discover many other useful applications in which they play a role.\r\n\r\n \r\n

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Learning Objectives<\/h3>\r\nComplex Numbers\r\n