Challenge Problem #7: Σ(x/(y^3+2))≥1

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Let $x,y,z$ be positive real numbers such that $xyz=1$. Prove that
$$\frac x{y^3+2}+\frac y{z^3+2}+\frac z{x^3+2}\ \geqslant\ 1.$$
 

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A hint ...

is requested (Giggle)
 

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