Tìm các số thực x,y thỏa mãn đẳng thức \(3x + y + 5xi = 2y - \left( {x - y} \right)i\):
A. \(\left\{ \begin{array}{l}x = 0\\y = 0\end{array} \right.\).
B. \(\left\{ \begin{array}{l}x = - \frac{1}{7}\\y = - \frac{4}{7}\end{array} \right.\).
C. \(\left\{ \begin{array}{l}x = \frac{4}{7}\\y = \frac{1}{7}\end{array} \right.\).
D. \(\left\{ \begin{array}{l}x = - \frac{4}{7}\\y = \frac{1}{7}\end{array} \right.\).
A. \(\left\{ \begin{array}{l}x = 0\\y = 0\end{array} \right.\).
B. \(\left\{ \begin{array}{l}x = - \frac{1}{7}\\y = - \frac{4}{7}\end{array} \right.\).
C. \(\left\{ \begin{array}{l}x = \frac{4}{7}\\y = \frac{1}{7}\end{array} \right.\).
D. \(\left\{ \begin{array}{l}x = - \frac{4}{7}\\y = \frac{1}{7}\end{array} \right.\).
$3x + y + 5xi = 2y - \left( {x - y} \right)i \Leftrightarrow \left\{ \begin{array}{l}3x + y = 2y\\5x = y - x\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}3x - y = 0\\6x - y = 0\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}x = 0\\y = 0\end{array} \right.$
Vậy chọn đáp án A.
Vậy chọn đáp án A.