Question

Calcule

a) (1/2)-³

b) (-7/4)-²

Answer 1

a) (1/2)-³ = (2/1)³ = 2.2.2 = 8 

b) (-7/4)-² = (-4/7)² = (-4)²/7² = 16/49             ok

Answer 2

 $a) (\frac{1}{2} )^{-3}=\frac{1}{(\frac{1}{2} )^{3}}=\frac{1}{\frac{1^3}{2^3} }=\frac{1}{\frac{1}{2.2.2} }=\frac{1}{\frac{1}{8} }\\ Conserva\ a\ de\ cima\ e\ multiplica\\ pelo\ inverso\ da\ de\ baixo\\Ficando: 1.\frac{8}{1}=8 \\ b) (\frac{-7}{4} )^{-2} =\frac{1}{(\frac{-7}{4} )^{2}}=\frac{1}{\frac{(-7)^2}{4^2} }=\frac{1}{\frac{(-7).(-7)}{4.4} }=\frac{1}{\frac{49}{16} }\\ Conserva\ a\ de\ cima\ e\ multiplica\\ pelo\ inverso\ da\ de\ baixo\\Ficando: 1.\frac{16}{49}= \frac{16}{49}$