8. Найдите значение выражения (√21-5)²+10/21

$$(\sqrt{21}-5)^2 + \frac{10}{21} = 21 - 10\sqrt{21} + 25 + \frac{10}{21} = 46 + \frac{10}{21} - 10\sqrt{21} = \frac{46*21 + 10}{21} - 10\sqrt{21} = \frac{976}{21} - 10\sqrt{21}$$.
Ответ: 976/21 - 10√21