Question

Tìm số tự nhiên n, biết :

a) \(\dfrac{16}{2^n}=2\)

b) \(\dfrac{\left(-3\right)^n}{81}=-27\)

c) \(8^n:2^n=4\)

Answer 1

a)

b)

c)

Answer 2

a) $\frac{16}{2^n}=\mathrm{2\; =>\; \backslash (\backslash dfrac\{2^4\}\{2^n\}=2\backslash Rightarrow2^\{4-n\}=2\backslash Rightarrow4-n=1\backslash Rightarrow\; n=3\backslash )}$

b,
\(\dfrac{\left(-3\right)^n}{81}=-27\Rightarrow\dfrac{\left(-3\right)^n}{\left(-3\right)^4}=-27\Rightarrow\left(-3\right)^{n-4}=\left(-3\right)^3\Rightarrow n-4=3\Rightarrow n=7\)

c,\(8^n:2^n=4\Rightarrow4^n=4\Rightarrow n=1\)

Answer 3

=> (-3)n-4 = (-3)3

=> n - 4 = 3 => n = 7

c) 8n : 2n = 4

4n = 4.

Answer 4

c) 8ⁿ : 4ⁿ = 4

= (8:4)ⁿ

=4ⁿ

4ⁿ =4¹

=> n =1