Resposta :
[tex]\frac{2^{- 2} + 2^{- 1}}{- 2^2} = \\\\ - \frac{\frac{1}{2^2} + \frac{1}{2^1}}{2^2} = \\\\ - \frac{\frac{1}{4_{/1}} + \frac{1}{2_{/2}}}{4} = \\\\ - \frac{\frac{1 + 2}{4}}{4} = \\\\ - \frac{3}{4} \div 4 = \\\\ - \frac{3}{4} \times \frac{1}{4} = \\\\ \boxed{- \frac{3}{16}}[/tex]