Bài 59 trang 26 SGK Toán 8 tập 1

Làm tính chia

a) \({5^3}:{( - 5)^2}\);             

b) \(\left ( \dfrac{3}{4} \right )^{5}\): \(\left ( \dfrac{3}{4} \right )^{3}\)           

c) \({( - 12)^3}:{8^3}\).

a) \({5^3}:{( - 5)^2} = {5^3}:{5^2} = {5^{3 - 2}} = 5\)

b) \(\left ( \dfrac{3}{4} \right )^{5}\): \(\left ( \dfrac{3}{4} \right )^{3}= \left ( \dfrac{3}{4} \right )^{5 -3}= \left ( \dfrac{3}{4} \right )^{2}\) \(= \dfrac{9}{16}\)

c) \({( - 12)^3}:{8^3} = {\left( { - \dfrac{{12}}{8}} \right)^3} = {\left( { - \dfrac{3}{2}} \right)^3} \)\(\,=  - \dfrac{{27}}{8}\)