Đáp án:
Giải thích các bước giải:
\(\begin{array}{l}
a - b = 2\left( {a + b} \right) = \frac{a}{b} = t\\
\Rightarrow \frac{a}{b} = t \Rightarrow a = bt\\
\Rightarrow \left\{ \begin{array}{l}
a - b = bt - b = b\left( {t - 1} \right)\\
2\left( {a + b} \right) = 2\left( {bt + b} \right) = b\left( {2t + 1} \right)
\end{array} \right.\\
\Rightarrow b\left( {t - 1} \right) = b\left( {2t + 1} \right)\\
\Leftrightarrow t - 1 = 2t + 1\\
\Leftrightarrow t = - 2\\
\Leftrightarrow \left\{ \begin{array}{l}
a - b = - 2\\
\frac{a}{b} = - 2
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
a = - 2b\\
- 2b - b = - 2
\end{array} \right.\\
\Leftrightarrow \left\{ \begin{array}{l}
a = - 2b\\
b = \frac{2}{3}
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
a = \frac{{ - 4}}{3}\\
b = \frac{2}{3}
\end{array} \right.
\end{array}\)
