Question

Thực hiện phép tính:

a) \({27^{\frac{2}{3}}} + {81^{ - 0,75}} - {25^{0,5}};\)

b) \({4^{2 - 3\sqrt 7 }}{.8^{2\sqrt 7 }}.\)

Answer 1

a: \(=3^2+\left(3^4\right)^{-0.75}-5^{2\cdot0.5}\)

\(=9-5+3^{-3}=4+\dfrac{1}{27}=\dfrac{109}{27}\)

b: \(=2^{4-6\sqrt{7}}\cdot2^{6\sqrt{7}}=2^{4-6\sqrt{7}+6\sqrt{7}}=2^4=16\)