Let \( T \) be defined by \( T(x) = Ax \), where
\[ A = \begin{bmatrix} 1 & -5 & -7 \\ -3 & 7 & 5 \end{bmatrix} \]
Find a vector \( x \) whose image under \( T \) is \( b \), where
\[ b = \begin{bmatrix} -2 \\ -2 \end{bmatrix} \]
and determine whether \( x \) is unique or not.