How to prove the following inequality for $n > 2$ and $ 0 < x < 1$:
$$(2n-1)x^{-1} + (2n+1)x^{2n-1} > \frac{(2n+1)^2}{2n}, \quad n \in \mathbb{N}, x \in \mathbb{R}$$
I tried using weighted arithmetic mean - geometric mean inequality, but then I end up with:
$$2n \sqrt[2n]{2n+1} \ge \frac{(2n + 1)^2}{2n}$$
which don't work.
Now, we need to prove that $$(2n+1)^{\frac{1}{2n}}>\left(\frac{2n+1}{2n}\right)^2$$ or $$\sqrt{2n+1}>\left(1+\frac{1}{2n}\right)^{2n},$$ which is obvious for any $n\geq4$.
Can you end it now?