Question

Докажите неравенстово 4ab≤ (a+b)²

Answer 1

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Answer 2

4ab<=(a+b)^2
4ab-(a+b)^2<=0
4ab-a^2-2ab-b^2=-a^2+2ab-b^2=
-(a^2-2ab+b^2)=-(a-b)^2
(a-b)^2>=0;-(a-b)^2<=0
4ab<=(a+b)^2