Question

Đề bài

Tính:

a)     \({\left( {\frac{1}{{256}}} \right)^{ - 0,75}} + {\left( {\frac{1}{{27}}} \right)^{ - \frac{4}{3}}}\)

b)    \({\left( {\frac{1}{{49}}} \right)^{ - 1,5}} - {\left( {\frac{1}{{256}}} \right)^{ - \frac{2}{3}}}\)

Answer 1

\(a,\left(\dfrac{1}{256}\right)^{-0,75}+\left(\dfrac{1}{27}\right)^{-\dfrac{4}{3}}\\ =256^{\dfrac{3}{4}}+27^{\dfrac{4}{3}}\\ =\sqrt[4]{256^3}+\sqrt[3]{27^4}\\ =145\\ b,\left(\dfrac{1}{49}\right)^{-1,5}-\left(\dfrac{1}{256}\right)^{-\dfrac{2}{3}}\\ =49^{\dfrac{3}{2}}-256^{\dfrac{2}{3}}\\ \simeq343-40,3\\ \simeq302,7\)