(a+b)²-(a-b)²

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[url=http://dmentrard.free.fr/GEOGEBRA/Maths/Export6/diffparcarreMD.html]http://dmentrard.free.fr/GEOGEBRA/Maths/Export6/diffparcarreMD.html[/url]

Information: (a+b)²-(a-b)²