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Graphing Linear Inequalities


Example 1:    Graph 2

  • Enter 2x + 1 into Y1
  • Arrow to the far left side of Y1
  • Hit ENTER until the "shade above" symbol
    is displayed.
  • Hit ZOOM #6 ZStandard (for a 10x10 window)
  • Graph
  • NOTE:  You will have to determine whether to draw a solid line or a dotted line for  y = 2x + 1.  This problem uses a solid line because of the "less than or equal to" sign.  The calculator will display a solid line at all times.
    (The Application program called "Inequalities" will display solid and dotted lines on the graphs.)

 


 1

3

Example 2:    Graph 5
  • Notice the "shade below" symbol to the far left of the Y1.
  • Again, you must determine whether to draw a solid or dotted line.  This problem uses a dotted line because it is strictly "less than" (no "equal to").

 

4

Example 3 Solve the system: 8
  • You will need to isolate the y variable in the second equation so that it can be entered into the calculator with the "shade above" indicated.

       Solving algebraically,
9
(be careful of the direction of the inequality symbol in this problem.)

  • The answer is the double shaded region on the graph.

 

6

7

 

Example 4: 
      Solve  12
  • Enter all three equations with appropriate "shade above" or "shade below" symbol.
  • Answer is the darkest shading.

13
            Zoom Decimal view.

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