Cho a, b, c > 0. CM:
a) $\frac{bc}{a}+\frac{ca}{b}+\frac{ab}{c}\geq a+b+c$
b) $\frac{a^2}{b^2+c^2}+\frac{b^2}{c^2+a^2}+\frac{c^2}{a^2+b^2}\geq\frac{a}{b+c}+\frac{b}{c+a} +\frac{c}{a+b}$
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Sinh Học lớp 12
