Question

Mọi người giúp tớ bài này nhé^^

Tìm x:

\(3^{x+4}\)+  \(3^{x+2}\)= 270

 

Answer 1

\(3^{x+4}+3^{x+2}=270\)

\(< =>3^x.81+3^x.9=270\)

\(< =>3^x=\frac{270}{90}=3< =>x=1\)

Answer 2

\(3^{x+4}+3^{x+2}=270\)

\(\Leftrightarrow3^x.81+3^x.9=270\)

\(\Leftrightarrow3^x\left(81+9\right)=270\)

\(\Leftrightarrow3^x.90=270\)

\(\Leftrightarrow3^x=3\)

\(\Leftrightarrow x=1\)

Answer 3

\(3^{x+4}+3^{x+2}=270\)

\(\Leftrightarrow3^x.81+3^x.9=270\Leftrightarrow3^x\left(81+9\right)=270\)

\(\Leftrightarrow3^x.90=270\Leftrightarrow3^x=3\Leftrightarrow x=1\)

Answer 4

3^x.3^4+3^x.3^2=270

3^x.81+3^x.9=270

3^x(81+9)=270

3^x.90=270

=>3^x=3

=>x=1

Answer 5

\(3^{x+4}+3^{x+2}=270\)

\(\Rightarrow3^{x+2+2}+3^{x+2}=270\)

\(\Rightarrow3^{x+2}\times3^2+3^{x+2}=270\)

\(\Rightarrow3^{x+2}\times\left(9+1\right)=270\)

\(\Rightarrow3^{x+2}\times10=270\)

\(\Rightarrow3^{x+2}=27\)

\(\Rightarrow3^{x+2}=3^3\)

\(\Rightarrow x+2=3\)

\(\Rightarrow x=1\)

Answer 6

3^{x + 4} + 3^{x + 2} = 270

=> 3^x . 81 + 3^x . 9 =270

=> 3^x .( 81 +9 ) =270

=> 3^x . 90 =270

=>3^x = 3      => x =1 

vậy x = 1