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uyen12376


Chứng minh các bđt sau:
a. Cho $x^2 +y^2=1$. CMR : $-\sqrt{2} \leq x+y \leq \sqrt{2}$
b. Cho $4x+y=1$. CMR : $4x^2+y^2 \geq \dfrac{1}{5}$
a. Cho $x^2 +y^2=1$. CMR : $-\sqrt{2} \leq x+y \leq \sqrt{2}$
b. Cho $4x+y=1$. CMR : $4x^2+y^2 \geq \dfrac{1}{5}$
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