Đáp án:
a) \(\left\{ \begin{array}{l}
y = \dfrac{{991}}{{329}}\\
x = - \dfrac{{1320}}{{329}}
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
a)\left\{ \begin{array}{l}
x + y = - 1\\
x - 657y = - 1983
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = - 1 - y\\
- 1 - y - 657y = - 1983
\end{array} \right.\\
\to \left\{ \begin{array}{l}
- 658y = - 1982\\
x = - 1 - y
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = \dfrac{{991}}{{329}}\\
x = - \dfrac{{1320}}{{329}}
\end{array} \right.\\
b)\left\{ \begin{array}{l}
x + y = 1\\
x - 657y = 1983
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 1 - y\\
1 - y - 567y = 1983
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 1 - y\\
- 568y = 1982
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = - \dfrac{{991}}{{284}}\\
x = \dfrac{{1275}}{{284}}
\end{array} \right.\\
c)\left\{ \begin{array}{l}
x + y = - 1983\\
x - 657y = - 1
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = - 1983 - y\\
- 1983 - y - 657y = - 1
\end{array} \right.\\
\to \left\{ \begin{array}{l}
- 658y = 1982\\
x = - 1983 - y
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = - \dfrac{{991}}{{329}}\\
x = - 1979,987842
\end{array} \right.\\
d)\left\{ \begin{array}{l}
x + y = 1983\\
x - 657y = 1
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 657y + 1\\
657y + 1 + y = 1983
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = \dfrac{{991}}{{329}}\\
x = 1979,987842
\end{array} \right.
\end{array}\)
