证明:a²+b+²c²+2ab+2bc+2ca=(a+b+c)²

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证明:a²+b+²c²+2ab+2bc+2ca=(a+b+c)²
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证明:a²+b+²c²+2ab+2bc+2ca=(a+b+c)²
证明:a²+b+²c²+2ab+2bc+2ca=(a+b+c)²

证明:a²+b+²c²+2ab+2bc+2ca=(a+b+c)²
a²+b+²c²+2ab+2bc+2ca
=a²+2ab+b² + 2bc+2ca + c²
=(a+b)² + 2c(a+b) + c²
=(a+b+c)²

移项做差。左边减右边的,等于零不就行了吗

(a+b+c)²=a²+2a(b+c)+(b+c)²=a²+2ab+2ca+b+²c²+2bc=a²+b+²c²+2ab+2bc+2ca