Problem 1. For all positive real numbers \( a, b, c \), prove that

 

\[
\frac{(a^2 + bc)^2}{b + c} + \frac{(b^2 + ca)^2}{c + a} + \frac{(c^2 + ab)^2}{a + b} \geq \frac{2abc(a + b + c)^2}{ab + bc + ca}.
\]

Solution 1. Solution 1
Solution 2. Solution 2
Solution 3. Solution 3