Question

Tìm x:

3^8x+4=81^x+3

Answer 1

`#3107`

\(3^{8x+4}=81^{x+3}\\ \Rightarrow3^{8x+4}=\left(3^4\right)^{x+3}\\ \Rightarrow3^{8x+4}=3^{4x+12}\\ \Rightarrow8x+4=4x+12\\ \Rightarrow8x-4x=12-4\\ \Rightarrow4x=8\\ \Rightarrow x=8\div4\\ \Rightarrow x=2\\ \text{Vậy, x = 2.}\)

Answer 2

Lời giải:

$3^{8x+4}=81^{x+3}$

$3^{8x+4}=(3^4)^{x+3}$

$3^{8x+4}=3^{4(x+3)}$

$\Rightarrow 8x+4=4(x+3)$
$\Rightarrow 2x+1=x+3$

$\Rightarrow x=2$

Answer 3

\(3^{8x+4}=81^{x+3}\)

\(\Rightarrow\left(3^4\right)^{2x+1}=81^{x+3}\)

\(\Rightarrow81^{2x+1}=81^{x+3}\)

\(\Rightarrow2x+1=x+3\)

\(\Rightarrow2x-x=3-1\)

\(\Rightarrow x=2\)