Horizontal Lines


The following numbers are wind chill tenperatures in Degrees Fahrenheit at Chicago's O'Hare airport one winter day in January of 1996.

Teperatures At A Given Time        Graph Of Windchill Temperatures
As you can see, for any value of x, we have y equal to 15. Thus the equation of the line is y = 15. Also note that the line is parallel to the x-axis.


Rule       Horizontal lines have a graph of y = b, where b is a constant.
Rule


Ex. Lets take a look at the following graphs. Place you mouse over the equation to see its graph.
Y = 2

Y = -2

Y = 4

Y = -4


Try writing two equations on your own. Look at the graphs corresponding to numbers 1 and 2. Enter the correct horizontal equation in each box (i.e. y = -20). When you are finished, click the Mark Now button

1.  Write the equation of the line.





2.  Write the equation of the line.



            
            



Try graphing some on your own. Go to the Graph-It applet below. Enter your own horizontal equations.
Ex. To graph Y = 5

  • Click on Set Graph
  • Set Range to -20, 20
  • Type in the number 5
  • Put a Check in the box next to the function
  • Now try any number between -20 and 20


    • Quick Hints:
    • X is the default domain variable.
    • Point to the graph to get exact values.


    Next Topic
    Previous Topic