Đề bài

Tính:

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

b)    ${\left( {\frac{1}{{49}}} \right)^{ - 1,5}} - {\left( {\frac{1}{{125}}} \right)^{ - \frac{2}{3}}}$

c)     $\left( {{4^{3 + \sqrt 3 }} - {4^{\sqrt 3  - 1}}} \right){.2^{ - 2\sqrt 3 }}$