Question

Tìm x

\(3^{x+2}+3^x=810\)

Answer 1

\(3^{x+2}+3^x=810\\ =>3^x.\left(3^2+1\right)=810\\ =>3^x=\dfrac{810}{3^2+1}=\dfrac{810}{10}=81=3^4\\ =>x=4\)

Answer 2

3^x+2 + 3^x = 810

<=> 3^x(3² + 1) = 810

<=> 3^x.10 = 810

<=> 3^x = 81 = 3⁴

<=> x = 4

Answer 3

\(3^{x+2}+3^x=810\)

`=>`\(3^x.3^2+3^x.1=810\)

`=>`\(3^x.\left(3^2+1\right)=810\)

`=>` \(3^x.10=810\)

`=>`\(3^x=810:10\)

`=>`\(3^x=81\)

`=>`\(3^x=3^4\)

`=>` \(x=4\)