Question 139
For the positive real numbers $a, b, c$, let $a b c=1$ apply. Prove the following inequality:
$$
\frac{a b}{a^{5}+a b+b^{5}}+\frac{b c}{b^{5}+b c+c^{5}}+\frac{c a}{c^{5}+c a+a^{5}} \leq 1
$$
$$
\frac{a b}{a^{5}+a b+b^{5}}+\frac{b c}{b^{5}+b c+c^{5}}+\frac{c a}{c^{5}+c a+a^{5}} \leq 1
$$