Question 39
Let $a$, $b$, $c$, $\lambda$ be positive real numbers with $\lambda \geq 1 / 4$. Show that
$$
\frac{a}{\sqrt{b^{2}+\lambda b c+c^{2}}}+\frac{b}{\sqrt{c^{2}+\lambda c a+a^{2}}}+\frac{c}{\sqrt{a^{2}+\lambda a b+b^{2}}} \geq \frac{3}{\sqrt{\lambda+2}}
$$
$$
\frac{a}{\sqrt{b^{2}+\lambda b c+c^{2}}}+\frac{b}{\sqrt{c^{2}+\lambda c a+a^{2}}}+\frac{c}{\sqrt{a^{2}+\lambda a b+b^{2}}} \geq \frac{3}{\sqrt{\lambda+2}}
$$