อ้างอิง:
ข้อความเดิมเขียนโดยคุณ Aroonsawad
prove that
$$\frac{1}{a^2+7ab+b^2} + \frac{1}{b^2+7bc+c^2} + \frac{1}{c^2+7ca+a^2} \geqslant \frac{1}{ab+bc+ca}$$ when a,b,c is positive real number  |
Divide and Conquer!
$\dfrac{1}{a^2+7ab+b^2}\geq\dfrac{c}{(a+b+c)(ab+bc+ca)}$