Question

- 512/343 = ( -8/7 ) ^n

( -3/4 ) ^n = 81/256

tìm số nguyên n

 

Answer 1

- 512/343 = ( -8/7 ) ^n

<=> (-8/7)^3=(-8/7)^n

<=>n=3

( -3/4 ) ^n = 81/256

<=>(-3/4)^n=(3/4)^4

<=>n=4

Answer 2

a) \(\frac{-512}{323}=\left(\frac{-8}{7}\right)^n\)

\(\Rightarrow\left(\frac{-8}{7}\right)^3=\left(\frac{-8}{7}\right)^n\)

\(\Rightarrow n=3\)

Vậy n = 3

b) \(\left(\frac{-3}{4}\right)^n=\frac{81}{256}\)

\(\Rightarrow\left(\frac{-3}{4}\right)^n=\left(\frac{-3}{4}\right)^4\)

\(\Rightarrow n=4\)

Vậy n = 4

_Chúc bạn học tốt_