Để so sánh $C$ và $D$, ta xét hiệu $C - D$:

$C = \dfrac{2025}{50^{10}} + \dfrac{2025}{50^8}$

$D = \dfrac{2026}{50^{10}} + \dfrac{2024}{50^8}$

$C - D = \left( \dfrac{2025}{50^{10}} - \dfrac{2026}{50^{10}} \right) + \left( \dfrac{2025}{50^8} - \dfrac{2024}{50^8} \right)$

$C - D = \dfrac{-1}{50^{10}} + \dfrac{1}{50^8}$

$C - D = \dfrac{-1}{50^{10}} + \dfrac{50^2}{50^{10}}$

$C - D = \dfrac{2500 - 1}{50^{10}}$

$C - D = \dfrac{2499}{50^{10}}$

Vì $\dfrac{2499}{50^{10}} > 0$, suy ra $C - D > 0$

Vậy $C > D$