Question

Tìm n thuộc IN

a) 2^3.2^n=2^6

b)7.7^n+1=343

Làm rồi mà sợ sai

Answer 1

a) 2³.2ⁿ = 2⁶

<=> 2³⁺ⁿ = 2⁶

<=> 3+n=6

<=> n = 3

b) 7.7ⁿ⁺¹ = 343

<=> 7¹⁺ⁿ⁺¹ = 7³

<=> 7²⁺ⁿ = 7³

<=> 2+n=3

<=> n = 1

Answer 2

a)2³*2ⁿ=2⁶

\(\Rightarrow2^{3+n}=2^6\)

\(\Rightarrow3+n=6\Rightarrow n=3\)

b)\(7\cdot7^{n+1}=343\)

\(\Rightarrow7^{n+2}=7^3\)

\(\Rightarrow n+2=3\Rightarrow n=1\)