tìm số phức z thỏa (2+i)^2×(1-z)=4-3i+(3+i) 15/10/2021 Bởi Brielle tìm số phức z thỏa (2+i)^2×(1-z)=4-3i+(3+i)
Đáp án: $\begin{array}{l}{\left( {2 + i} \right)^2}.\left( {1 – z} \right) = 4 – 3i + \left( {3 + i} \right)\\ \Rightarrow \left( {4 + 4i + {i^2}} \right).\left( {1 – z} \right) = 7 – 2i\\ \Rightarrow \left( {4 + 4i – 1} \right).\left( {1 – z} \right) = 7 – 2i\\ \Rightarrow 1 – z = \dfrac{{7 – 2i}}{{3 + 4i}}\\ \Rightarrow 1 – z = \dfrac{{13}}{{25}} – \dfrac{{34}}{{25}}i\\ \Rightarrow z = 1 – \dfrac{{13}}{{25}} + \dfrac{{34}}{{25}}i\\ \Rightarrow z = \dfrac{{12}}{{25}} + \dfrac{{34}}{{25}}i\end{array}$ Bình luận
Đáp án:
$\begin{array}{l}
{\left( {2 + i} \right)^2}.\left( {1 – z} \right) = 4 – 3i + \left( {3 + i} \right)\\
\Rightarrow \left( {4 + 4i + {i^2}} \right).\left( {1 – z} \right) = 7 – 2i\\
\Rightarrow \left( {4 + 4i – 1} \right).\left( {1 – z} \right) = 7 – 2i\\
\Rightarrow 1 – z = \dfrac{{7 – 2i}}{{3 + 4i}}\\
\Rightarrow 1 – z = \dfrac{{13}}{{25}} – \dfrac{{34}}{{25}}i\\
\Rightarrow z = 1 – \dfrac{{13}}{{25}} + \dfrac{{34}}{{25}}i\\
\Rightarrow z = \dfrac{{12}}{{25}} + \dfrac{{34}}{{25}}i
\end{array}$