Question

3^x+2+3^x=90

Answer 1

\(3^{x+2}+3^x=90\)

\(\Rightarrow3^x.3^2+3^x=90\)

\(\Rightarrow3^x\left(3^2+1\right)=90\)

\(\Rightarrow3^x.10=90\)

\(\Rightarrow3^x=9\)

\(\Rightarrow3^x=3^2\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

Answer 2

x=2 chuan cmld

Answer 3

3^{x + 2} + 3^x = 90

=> 3^x . 3² + 3^x = 90

=> 3^x ( 3^{2 +} 1 ) = 90

=> 3^x . 10 = 90

=> 3^x = 90:10

=> 3^x = 9

=> 3^x = 3² ( t/_m)

Vậy x=2