Question

mong mọi người giúp mình

Answer 1

\(a,\Leftrightarrow3^{x-2}\left(18+3^2\right)=243\\ \Leftrightarrow3^{x-2}=243:27=9=3^2\\ \Leftrightarrow x-2=2\Leftrightarrow x=4\)

Answer 2

\(18\cdot3^{x-2}+3^x=243\)

\(\Leftrightarrow3^{x+1}=243\)

hay x=4

Answer 3

\(18.3^{x-2}+3^x=243\)

=> \(3^2.2.3^x:3^2+3^x=243\)

\(\Rightarrow2.3^x+3^x=243\)

=> \(3^{x+1}=243=3^5\)

=> x + 1 = 5

=> x = 4