Inequalities: Difference between revisions

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To graph inequalities of the "less than" form
"ax + by + c <= 0"
<source lang="javascript">
var line = board.create('line', [c, b, a]),
ineq = board.create('inequality', [line]);
</source>
If one wants to show "greater than" i.e.  "ax + by + c >= 0" , ''inverse:true'' has to be used:
<source lang="javascript">
var line = board.create('line', [c, b, a]),
ineq = board.create('inequality', [line], {inverse:true});
</source>
In the following example, two lines are shown.
The first, blue line has the equation "y = 2x + 3" or "2x - 1y + 3 = 0",
the second, black line has the equation "x = 3" or "1x + 0y - 3 = 0".
For these equations, the inequalities plotted are
"2x - y + 3 <= 0" (less than form hence don't add "inverse: true") - yellow region
and
"1x + 0y - 3 >= 0" (greater than form hence do add "inverse: true") - red region.
<jsxgraph width="400" height="400" box="box1">
<jsxgraph width="400" height="400" box="box1">
(function() {
(function() {
var b = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 5, 5, -5], axis:true});
    var b = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 5, 5, -5], axis:true});
var c = b.create('slider', [[-3,4], [2,4], [-5,0,5]]),
    var line1 = b.create('line', [3, 2, -1]), // Line y = 2x + 3 or 2x - 1y + 3 = 0
    line1 = b.create('line', [function() { return [c.Value(), 0, -1]; }], {strokeColor: 'black'}),
     ineq1 = b.create('inequality', [line1], {fillColor: 'yellow'});  //This would plot the inequality 2x - y + 3 <= 0
     ineq1 = b.create('inequality', [line1], {inverse: true}),


     line2 = b.create('line', [1, 2, -1]),
     var line2 = b.create('line', [-3, 1, 0], {strokeColor: 'black'}); // Line x = 3 or 1x + 0y - 3 = 0
     ineq2 = b.create('inequality', [line2], {inverse: true});
     var ineq2 = b.create('inequality', [line2], {inverse: true, fillColor: 'red'}); //This would plot the inequality 1x + 0y - 3 >= 01x + 0y - 3 >= 0


})();
})();
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===The JavaScript code===
===The JavaScript code===
<source lang="javascript">
<source lang="javascript">
var b = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 5, 5, -5], axis:true});
    var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 5, 5, -5], axis:true});
var c = b.create('slider', [[-3,4], [2,4], [-5,0,5]]),
    var line1 = board.create('line', [3, 2, -1]), // Line y = 2x + 3 or 2x - 1y + 3 = 0
    line1 = b.create('line', [function() { return [c.Value(), 0, -1]; }], {strokeColor: 'black'}),
     ineq1 = board.create('inequality', [line1], {fillColor: 'yellow'}); //This would plot the inequality 2x - y + 3 <= 0
     ineq1 = b.create('inequality', [line1], {inverse: true}),
 
    line2 = b.create('line', [1, 2, -1]),
    ineq2 = b.create('inequality', [line2], {inverse: true});


    var line2 = board.create('line', [-3, 1, 0], {strokeColor: 'black'}); // Line x = 3 or 1x + 0y - 3 = 0
    var ineq2 = board.create('inequality', [line2], {inverse: true, fillColor: 'red'});  //This would plot the inequality 1x + 0y - 3 >= 0
</source>
</source>


[[Category:Examples]]
[[Category:Examples]]
[[Category:Calculus]]
[[Category:Calculus]]

Latest revision as of 09:57, 8 June 2017

To graph inequalities of the "less than" form "ax + by + c <= 0"

var line = board.create('line', [c, b, a]),
ineq = board.create('inequality', [line]);

If one wants to show "greater than" i.e. "ax + by + c >= 0" , inverse:true has to be used:

var line = board.create('line', [c, b, a]),
ineq = board.create('inequality', [line], {inverse:true});

In the following example, two lines are shown. The first, blue line has the equation "y = 2x + 3" or "2x - 1y + 3 = 0", the second, black line has the equation "x = 3" or "1x + 0y - 3 = 0".

For these equations, the inequalities plotted are "2x - y + 3 <= 0" (less than form hence don't add "inverse: true") - yellow region and "1x + 0y - 3 >= 0" (greater than form hence do add "inverse: true") - red region.

The JavaScript code

    var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 5, 5, -5], axis:true});
    var line1 = board.create('line', [3, 2, -1]), // Line y = 2x + 3 or 2x - 1y + 3 = 0
    ineq1 = board.create('inequality', [line1], {fillColor: 'yellow'});  //This would plot the inequality 2x - y + 3 <= 0

    var line2 = board.create('line', [-3, 1, 0], {strokeColor: 'black'}); // Line x = 3 or 1x + 0y - 3 = 0
    var ineq2 = board.create('inequality', [line2], {inverse: true, fillColor: 'red'});  //This would plot the inequality 1x + 0y - 3 >= 0