Tính a) (2/5 + 1/2)^2; b) (0,75 - 1 1/2)^3; c) (3/5)^15 : (0,36)^5

* Hướng dẫn giải

a) ${\left(\frac{2}{5}+\frac{1}{2}\right)}^2={\left(\frac{4}{10}+\frac{5}{10}\right)}^2={\left(\frac{9}{10}\right)}^2=\frac{9^2}{{10}^2}=\frac{81}{100}$

b) ${\left(0,75-1\frac{1}{2}\right)}^3={\left(\frac{3}{4}-\frac{3}{2}\right)}^3={\left(\frac{3}{4}-\frac{6}{4}\right)}^3={\left(\frac{-3}{4}\right)}^3=\frac{{\left(-3\right)}^3}{4^3}=\frac{-27}{64}$

 =315515:32525=315515:310510=315515.510310=315.510515.310=3555=355

d) ${\left(1-\frac{1}{3}\right)}^8:{\left(\frac{4}{9}\right)}^3={\left(\frac{2}{3}\right)}^8:{\left[{\left(\frac{2}{3}\right)}^2\right]}^3$

$={\left(\frac{2}{3}\right)}^8:{\left(\frac{2}{3}\right)}^{2.3}={\left(\frac{2}{3}\right)}^8:{\left(\frac{2}{3}\right)}^6$

$={\left(\frac{2}{3}\right)}^{8-6}={\left(\frac{2}{3}\right)}^2$