(a+b)²=a²+2ab+b²
http://dmentrard.free.fr/GEOGEBRA/Maths/Export6/(a+b)%C2%B2MD.html
[url=http://dmentrard.free.fr/GEOGEBRA/Maths/Export6/(a+b)%C2%B2MD.html]http://dmentrard.free.fr/GEOGEBRA/Maths/Export6/(a+b)%C2%B2MD.html[/url]
Information: (a+b)²=a²+2ab+b²