CHO MÌNH HỎI CÂU I,j với khó quá

i/
$\displaystyle  \begin{array}{{>{\displaystyle}l}}
( x+1)^{6} =2^{6} .3^{3}\\
\Leftrightarrow ( x+1)^{6} =\left( 2\sqrt{3}\right)^{6}\\
\Leftrightarrow \left[ \begin{array}{l l}
x+1=2\sqrt{3} & \\
x+1=-2\sqrt{3} & 
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l l}
x=2\sqrt{3} -1 & \\
x=-2\sqrt{3} -1 & 
\end{array} \right.\\
\end{array}$
j/
$\displaystyle  \begin{array}{{>{\displaystyle}l}}
3^{x+3} -234=3^{x}\\
\Leftrightarrow 3^{x+3} -3^{x} =234\\
\Leftrightarrow 3^{x}\left( 3^{3} -1\right) =234\\
\Leftrightarrow 3^{x} .26=234\\
\Leftrightarrow 3^{x} =234:26\\
\Leftrightarrow 3^{x} =9\\
\Leftrightarrow 3^{x} =3^{2}\\
\Leftrightarrow x=2\\
\end{array}$