a. Use a graphing utility to graph y - 2x2 - 82.r + 720 in a standard e\\~ng rectangle

Chapter 3, Problem 81

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a. Use a graphing utility to graph y - 2x2 - 82.r + 720 in a standard e\\~ng rectangle. What do you observe? b. Find the coordinates of the vertex for the given quadratic function. c. ll1e answer to part (b) is (20.5, - 120.5). Because the leading coef-fic.ient, 2. of the given function is positive, the vertex is a minimum point on the graph. Use this fact to help find a viewing rectangle lhat will give a relatively complete picture of the parabola. With an axis of symmetry at x - 20.5, the setting for x should extend past this, so try X min - 0 and X max - 30. The setting for y should include (and probably go below) the )'coordinate of the graph's minimum . ..v-vaJue. so try Ymin - - 130. Expe riment with Y max until your utility shows the parabola's major features. d. [n general, explain how knowing the coordinates of a parabola's vertex can help detcnnine a reasonable viewing rectangle on a graphing utility for obta ining a complete picture of the parabola.