We suggest that you use a function calculator or a function machine to develop a table of points for different input values. This applet calculates the five points from the initial value that you may want (input). By default there are three points on the graph, drag these points to any of these points on the table. When all the three points concur with the points on the table, straight line will appear. Clear to practice the next line. (Zoom in or Zoom Out tool is active in case you need)