Hãy tính:
a) \({9^{\frac{2}{5}}}{.27^{\frac{2}{5}}} - {144^{\frac{3}{4}}}:{9^{\frac{3}{4}}}\)
b) \({\left( {\frac{1}{{16}}} \right)^{ - 0,75}} + 0,{25^{ - \frac{5}{2}}}\)
- Viết các số dưới dạng lũy thừa.
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- Áp dụng: \({a^n}.{b^n} = {\left( {a.b} \right)^n};\,{a^n}:{b^n} = {\left( {\frac{a}{b}} \right)^n}\) ; \({\left( {{a^n}} \right)^m} = {a^{n.m}};\,{a^n}.{a^m} = {a^{n + m}};{a^{ - n}} = \frac{1}{{{a^n}}}\)
a)
\(\begin{array}{l}{9^{\frac{2}{5}}}{.27^{\frac{2}{5}}} - {144^{\frac{3}{4}}}:{9^{\frac{3}{4}}}\\ = {243^{\frac{2}{5}}} - {16^{\frac{3}{4}}} = {\left( {{3^5}} \right)^{\frac{2}{5}}} - {\left( {{2^4}} \right)^{\frac{3}{4}}}\\ = {3^2} - {2^3} = 9 - 8 = 1\end{array}\)
b)
\(\begin{array}{l}{\left( {\frac{1}{{16}}} \right)^{ - 0,75}} + 0,{25^{ - \frac{5}{2}}}\\ = {\left( {{2^{ - 4}}} \right)^{ - \frac{3}{4}}} + {\left( {\frac{1}{4}} \right)^{ - \frac{5}{2}}} = {2^3} + {\left( {{2^{ - 2}}} \right)^{ - \frac{5}{2}}}\\ = 8 + {2^5} = 8 + 32 = 40\end{array}\)