Tính a) (2/3)^3 - 4.(-1 3/4)^2 + (-2/3)^3 b) (-0,5)^5 : (-0,5)^3

* Hướng dẫn giải

a) ${\left(\frac{2}{3}\right)}^3-4.{\left(-1\frac{3}{4}\right)}^2+{\left(-\frac{2}{3}\right)}^3={\left(\frac{2}{3}\right)}^3-{\left(\frac{2}{3}\right)}^3-4{\left(-\frac{7}{4}\right)}^2$$=-4.\frac{49}{16}=-\frac{49}{4}$

b) ${\left(-0,5\right)}^5:{\left(-0,5\right)}^3-{\left(\frac{17}{2}\right)}^7:{\left(\frac{17}{2}\right)}^6={\left(-0,5\right)}^2-\frac{17}{2}$$=\frac{1}{4}-\frac{17}{2}=-\frac{33}{4}$