Question 44
Prove that
$$
1 \le \frac{(x+y)(x^3+y^3)}{(x^2+y^2)^2} \le \frac{9}{8}
$$
for all positive real numbers $x$ and $y$.
$$
1 \le \frac{(x+y)(x^3+y^3)}{(x^2+y^2)^2} \le \frac{9}{8}
$$
for all positive real numbers $x$ and $y$.
MathNet 2011 Question 44
Math Olympiad Vault · MathNet 2011