a)
$\,2^{\large -3}\,=\,\dfrac{1}{2^{\large 3}}\,=\,\dfrac{1}{2\centerdot 2 \centerdot 2}\,=\,\dfrac{1}{8}\,=\,0,125\,$
b)
$\,(-2)^{\large -3}\,=\,\dfrac{1}{(-2)^{\large 3}}\,=\,\dfrac{1}{(-2)\centerdot (-2) \centerdot (-2)}\,=\,\dfrac{1}{(-8)}\,=\,-\,\dfrac{1}{8}\,=\,-0,125\,$
a)
$\,-2^{\large -3}\,=\,-\dfrac{1}{2^{\large 3}}\,=\,-\dfrac{1}{2\centerdot 2 \centerdot 2}\,=\,-\dfrac{1}{8}\,=\,-0,125\,$
