Đáp án:
\(A=- \dfrac{1}{20} - \dfrac{57}{20}i\)
Giải thích các bước giải:
\(\begin{array}{l}
z_1 = 4 + 3i;\quad z_2 = 2 - 3i\\
A = \dfrac{z_1.z_2}{z_1 -z_2}\\
\quad = \dfrac{(4+3i)(2-3i)}{4 + 3i - (2 - 3i)}\\
\quad =\dfrac{8 -6i - 9i^2}{2 +6i}\\
\quad = \dfrac{17 - 6i}{2 + 6i}\\
\quad = \dfrac{(17 - 6i)(2 - 6i)}{(2 + 6i)(2 - 6i)}\\
\quad = \dfrac{34 -114i + 36i^2}{4 - 36i^2}\\
\quad = \dfrac{-2 - 114i}{40}\\
\quad = - \dfrac{1}{20} - \dfrac{57}{20}i
\end{array}\)
