Đáp án:
$\begin{array}{l}
{\left( {2 + i} \right)^2}.\left( {1 - z} \right) = 4 - 3i + \left( {3 + i} \right)\\
\Rightarrow \left( {4 + 4i + {i^2}} \right).\left( {1 - z} \right) = 7 - 2i\\
\Rightarrow \left( {4 + 4i - 1} \right).\left( {1 - z} \right) = 7 - 2i\\
\Rightarrow 1 - z = \dfrac{{7 - 2i}}{{3 + 4i}}\\
\Rightarrow 1 - z = \dfrac{{13}}{{25}} - \dfrac{{34}}{{25}}i\\
\Rightarrow z = 1 - \dfrac{{13}}{{25}} + \dfrac{{34}}{{25}}i\\
\Rightarrow z = \dfrac{{12}}{{25}} + \dfrac{{34}}{{25}}i
\end{array}$
