3x+1 + 2x.3x - 18x - 27 = 0
=> 3x.3 + 2x.3x - (18x + 27) = 0
=> 3x.(3 + 2x) - 9.(2x + 3) = 0
=> (2x + 3).(3x - 9) = 0
\(\Rightarrow\orbr{\begin{cases}2x+3=0\\3^x-9=0\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}2x=-3\\3^x=9\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x=\frac{-3}{2}\\x=2\end{cases}}\)
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