advertisement

10/7/2010 Section 1.1 Graphs and Graphing Utilities Plot points on the rectangular coordinate system. Plot the x coordinate first then the y coordinate. This is an ordered pair of real numbers. (x,y) The graph of an equation in two variables is the set of all points whose coordinates satisfy the equation. y y = x2 − 3 4 3 2 1 x −4 −3 −2 −1 1 −1 −2 −3 2 3 4 5 x -2 -1 0 1 2 y 1 -2 -3 -2 1 −4 1 10/7/2010 Example Graph the following equation and construct a table: y = x − 2 y x 4 y 3 2 1 x −4 −3 −2 −1 1 2 3 4 5 −1 −2 −3 −4 Graphing Calculators or graphing software packages for computers are referred to as graphing utilities or graphers. Below you will find the viewing rectangle. Graphing Calculator The Viewing Rectangle The meaning of the terms is demonstrated at right. This is the window that you get with the dimensions chosen by pressing Window in the top row of keys on your calculator. Ymax Xscl Xmax Xmin Yscl Ymin The Xscl and Yscl are the spacing between tick marks. We express this window’s dimensions as [-8,8,1] by [-4,10,1]. X dimensions are first and Y dimensions second. To get the standard window [-10,10,1] x [-10,10,1] press Zoom, then the number 6, for Zoom Standard. 2 10/7/2010 Graphing Calculator Making a Table Press the blue key in the upper left corner that says y= Now type in the equation. θ then X2 then X,T,,,,n ÷and finally 9 Press 2nd Window in order to Set up the Table. Press 2nd Graph to see the Table of values. Example Given the following viewing window, put the numbers on the screen. [-50,50,10] by[-40,40,10] x Y intercept The x and y intercepts can be seen on a graphing calculator 3 10/7/2010 For the x intercept, the y-coordinate is 0. ( For the y intercept, the x-coordinate is 0. ( 0, ,0) ) y y = x2 − 4 4 3 x y 2 0 1 x −4 −3 −2 −1 1 2 3 4 5 0 −1 −2 −3 What are the x and y intercepts? −4 Find the x and y intercepts and graph the equation after plotting a few more points. Example y y = x+2 4 3 x y 2 0 1 x −4 −3 −2 −1 1 2 3 4 5 0 −1 −2 −3 −4 1. What is the desirable heart rate of a 20 year old woman during exercise? 2. What is the desirable heart rate of a 20 year old man during exercise? 4