Đáp án:
b) \(\left\{ \begin{array}{l}
x = 2\\
y = - 1
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
C13:\\
a)\left\{ \begin{array}{l}
2x + y = 4\\
x - 2y = - 3
\end{array} \right.\\
\to \left\{ \begin{array}{l}
4x + 2y = 8\\
x - 2y = - 3
\end{array} \right.\\
\to \left\{ \begin{array}{l}
5x = 5\\
x - 2y = - 3
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 1\\
y = 2
\end{array} \right.\\
b)\left\{ \begin{array}{l}
2x - 3y = 7\\
3x + 4y = 2
\end{array} \right.\\
\to \left\{ \begin{array}{l}
8x - 12y = 28\\
9x + 12y = 6
\end{array} \right.\\
\to \left\{ \begin{array}{l}
17x = 34\\
2x - 3y = 7
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 2\\
y = - 1
\end{array} \right.
\end{array}\)
