# Difference between revisions of "Inequalities"

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A WASSERMANN (talk | contribs) |
A WASSERMANN (talk | contribs) |
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− | To graph inequalities of the form | + | To graph inequalities of the "less than" form |

− | + | "ax + by + c <= 0" | |

− | |||

<source lang="javascript"> | <source lang="javascript"> | ||

− | line = | + | var line = board.create('line', [c, b, a]), |

− | ineq = | + | ineq = board.create('inequality', [line]); |

</source> | </source> | ||

− | + | ||

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

<source lang="javascript"> | <source lang="javascript"> | ||

− | line = | + | var line = board.create('line', [c, b, a]), |

− | ineq = | + | ineq = board.create('inequality', [line], {inverse:true}); |

</source> | </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 | + | var line1 = b.create('line', [3, 2, -1]), // Line y = 2x + 3 or 2x - 1y + 3 = 0 |

− | + | ineq1 = b.create('inequality', [line1], {fillColor: 'yellow'}); //This would plot the inequality 2x - y + 3 <= 0 | |

− | ineq1 = b.create('inequality', [line1], { | ||

− | line2 = b.create('line', [1, | + | var line2 = b.create('line', [-3, 1, 0], {strokeColor: 'black'}); // Line x = 3 or 1x + 0y - 3 = 0 |

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

})(); | })(); | ||

Line 29: | Line 35: | ||

===The JavaScript code=== | ===The JavaScript code=== | ||

<source lang="javascript"> | <source lang="javascript"> | ||

− | var | + | var board = JXG.JSXGraph.initBoard('box1', {boundingbox: [-5, 5, 5, -5], axis:true}); |

− | var | + | 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 | ||

</source> | </source> | ||

[[Category:Examples]] | [[Category:Examples]] | ||

[[Category:Calculus]] | [[Category:Calculus]] |

## Latest revision as of 10:57, 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
```