Bài 1 :
a. \(\left(a^m\right)^n=a^{m\cdot n}\)
\(a^m:a^n=a^{m-n}\)
b.\(\left(\left(-\dfrac{1}{2}^3\right)^2\right):\dfrac{\left(\dfrac{2}{3}\right)^7}{\left(\dfrac{2}{3}\right)^5}=-\dfrac{1}{2}^6:\dfrac{2}{3}^2=\dfrac{1}{64}:\dfrac{4}{9}=\dfrac{1\cdot9}{64\cdot4}=\dfrac{9}{256}\)
Bài 2 :
a. \(\dfrac{2}{5}\cdot17\cdot\dfrac{1}{3}-\dfrac{2}{5}\cdot47\cdot\dfrac{1}{3}=\dfrac{1}{3}\left(\dfrac{2}{5}\left(17-47\right)\right)=\dfrac{1}{3}\left(\dfrac{2}{5}\cdot\left(-30\right)\right)=\dfrac{1}{3}\left(-12\right)=-4\)
b. \(\left(\dfrac{6}{5}-\dfrac{2}{7}\right)+15:\dfrac{35}{2^2}=\dfrac{32}{35}+\dfrac{12}{7}=\dfrac{92}{35}\)
Bài 3 :
a. \(-x+\dfrac{4}{9}=\dfrac{2}{27}\\ \Rightarrow-x=\dfrac{2}{27}-\dfrac{4}{9}=-\dfrac{10}{27}\\ x=\dfrac{10}{27}\)
