Question

tiính hoặc rút gọn các biểu thức 

a) \(\sqrt[4]{\left(-\dfrac{4}{5}\right)^4}\)

b) \(\dfrac{\sqrt{4}}{\sqrt{5}}\)

c) \(\left(\sqrt[3]{9}\right)^2\)

d) \(\sqrt[5]{\sqrt{a}}\)

e) \(\sqrt[3]{2^6}\)

Answer 1

a: \(\sqrt[4]{\left(-\dfrac{4}{5}\right)^4}=\left|-\dfrac{4}{5}\right|=\dfrac{4}{5}\)

b: \(\dfrac{\sqrt{4}}{\sqrt{5}}=\sqrt{\dfrac{4}{5}}=\dfrac{2}{\sqrt{5}}=\dfrac{2\sqrt{5}}{5}\)

c: \(\left(\sqrt[3]{9}\right)^2=\left(9^{\dfrac{1}{3}}\right)^2=9^{\dfrac{2}{3}}\)

d: \(\sqrt[5]{\sqrt{a}}=\sqrt[5]{a^{\dfrac{1}{2}}}=a^{\dfrac{1}{2}\cdot\dfrac{1}{5}}=a^{\dfrac{1}{10}}\)

e: \(\sqrt[3]{2^6}=\sqrt[3]{\left(2^2\right)^3}=2^2=4\)