For positive real numbers $a,b,c$ and a positive integer $n$ define $\displaystyle d_n=2\sqrt[n]{a}-\sqrt[n]{b}-\sqrt[n]{c}$. For which $a,b,c$ the series $\displaystyle \sum_{n=1}^{\infty}d_n$ converges? We did not receive any solutions. For a detailed solution see the following link {{:pow:2026sproblem6.pdf|Solution}}.