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MathNet 2012 Question 38

Math Olympiad Vault · MathNet 2012

Question 38

Let $a,b,c$ be positive real numbers with $a^2+b^2+c^2\ge3$. Prove
$$\frac{(a+1)(b+2)}{(b+1)(b+5)}+\frac{(b+1)(c+2)}{(c+1)(c+5)}+\frac{(c+1)(a+2)}{(a+1)(a+5)}\ge\frac32.$$