Đáp án:
\(\begin{array}{l}
a)\,\,\left\{ \begin{array}{l}
x = - 2\\
y = 3
\end{array} \right.\\
b)\,\,\left\{ \begin{array}{l}
x = - \frac{{19}}{{13}}\\
y = - \frac{{48}}{{13}}
\end{array} \right.
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a)\,\,\left\{ \begin{array}{l}
x + 2y = 4\\
4x - 3y = - 17
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
4x + 8y = 16\\
4x - 3y = - 17
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x = 4 - 2y\\
11y = 33
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x = 4 - 2y\\
y = 3
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x = - 2\\
y = 3
\end{array} \right..\\
b)\,\,\left\{ \begin{array}{l}
- 3x + 2y + 3 = 0\\
x - 5y = 17
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
3x - 2y = 3\\
x - 5y = 17
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
3x - 2y = 3\\
3x - 15y = 51
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
13y = - 48\\
x = 17 + 5y
\end{array} \right.\\
\Leftrightarrow \left\{ \begin{array}{l}
x = 17 + 5y\\
y = - \frac{{48}}{{13}}
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
x = - \frac{{19}}{{13}}\\
y = - \frac{{48}}{{13}}
\end{array} \right..
\end{array}\)
