(a+b)²=a²+2ab+b²
(a-b)²=a²-2ab+b²
(a+b)(a-b)=a²-b²
(a+b)³=a³+3a²b+3ab²+b³
(a-b)³=a³-3a²b+3ab²-b³
(a+b+c)²=a²+b²+c²+2ab+2bc+2ca

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