giúp mình với !!

$\displaystyle  \begin{array}{{>{\displaystyle}l}}
a)( x-3)^{2} =( 3+x)^{2}\\
\Longrightarrow \left[ \begin{array}{l l}
x-3 & =x+3\\
x-3 & =-x-3
\end{array} \right.\\
\Longrightarrow x=0\\
b) 1-9x^{2} =( 3x+1)^{2}\\
\Longrightarrow ( 1-3x)( 1+3x) =( 1+3x)^{2}\\
\Longrightarrow \left[ \begin{array}{l l}
1+3x & =0\\
1-3x & =1+3x
\end{array} \right.\\
\Longrightarrow \left[ \begin{array}{l l}
x & =\frac{-1}{3}\\
x & =0
\end{array} \right.\\
c) x^{2}( x+8) +x^{2} =-8x\\
\Longrightarrow x^{2}( x+9) =-8x\\
\Longrightarrow \left[ \begin{array}{l l}
x & =0\\
x^{2} +9x+8 & =0
\end{array} \right.\\
\Longrightarrow \left[ \begin{array}{l l}
x & =8\\
x & =-1\\
x & =-8
\end{array} \right.
\end{array}$