Question

Viết các số \(\left(\dfrac{1}{9}\right)^5;\left(\dfrac{1}{27}\right)^7\)dưới dạng lũy thừa cơ số \(\dfrac{1}{3}\)

Answer 1

\(\left(\dfrac{1}{9}\right)^5=\left(\dfrac{1}{3}\right)^{10}\\ \left(\dfrac{1}{27}\right)^7=\left(\dfrac{1}{3}\right)^{21}\)

Answer 2

Giải :

\(\left(\dfrac{1}{9}\right)^5=\left[\left(\dfrac{1}{3}\right)^2\right]^5=\left(\dfrac{1}{3}\right)^{2\times5}=\left(\dfrac{1}{3}\right)^{10}\\ \left(\dfrac{1}{27}\right)^7=\left[\left(\dfrac{1}{3}\right)^3\right]^7=\left(\dfrac{1}{3}\right)^{3\times7}=\left(\dfrac{1}{3}\right)^{21}\)

Answer 3

`(1/9)^5`

`=` `[(1/3)^2]^5`

`=` `(1/3)^(2.5)`

`=` `(1/3)^10`

____

`(1/27)^7`

`=` `[(1/3)^3]^7`

`=` `(1/3)^(3.7)`

`=` `(1/3)^21`

`->` Lũy thừa của lũy thừa: `(x^m)^n=x^(m.n)`