$2(\frac{a^{2}}{b^{2}}+\frac{b^{2}}{c^{2}}+\frac{c^{2}}{a^{2}})-2(\frac{a}{b}+\frac{b}{c}+\frac{c}{a})=(\frac{a}{b}-1)^{2}+(\frac{b}{c}-1)^{2}+(\frac{c}{a}-1)^{2}+\frac{a^{2}}{b^{2}}+\frac{b^{2}}{c^{2}}+\frac{c^{2}}{a^{2}}-3 \geq 0 \Rightarrow đpcm$
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