Thread: A math puzzle
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Old November 20 2012, 02:16 PM   #8
Shaytan
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Re: A math puzzle

#2 to #3 is what we call in French identité remarquable, must have a name in English too, it's supposed to be known by heart to use it to solve simple equations:

(a+b)Č= aČ+2ab+bČ
(a-b)Č=aČ-2ab+bČ
(a-b)(a+b)=aČ-bČ
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