8) Вычислим: $$25^{\frac{1}{2}} + (0.25)^{-\frac{1}{2}} - 81^{\frac{1}{4}}$$.
$$25^{\frac{1}{2}} = \sqrt{25} = 5$$
$$(0.25)^{-\frac{1}{2}} = (\frac{1}{4})^{-\frac{1}{2}} = 4^{\frac{1}{2}} = \sqrt{4} = 2$$
$$81^{\frac{1}{4}} = \sqrt[4]{81} = 3$$
$$5 + 2 - 3 = 4$$
Ответ: 4