Question

tìm n thuộc Z biết

a) (1/2)^n=1/32

b)343/125=(7/5)^n

c)1/9.27=3^n

d)3^-2.3^4.3^n=3^7

giúp mk

Answer 1

a) \(\left(\dfrac{1}{2}\right)^n=\dfrac{1}{32}\)

\(\Rightarrow\left(\dfrac{1}{2}\right)^n=\dfrac{1^5}{2^5}\)

\(\Rightarrow n=5\)

Vậy n = 5

Answer 2

c) \(\dfrac{1}{9}\cdot27=3^n\)

\(\Rightarrow3=3^n\)

\(\Rightarrow n=1\)

Vậy n = 1

Answer 3

d) \(3^{-2}\cdot3^4\cdot3^n=3^7\)

\(\Rightarrow3^2\cdot3^n=3^7\)

\(\Rightarrow3^n=3^5\)

\(\Rightarrow n=5\)

Vậy n = 5