Đáp án:
\(\left\{ \begin{array}{l}
x = 50\\
y = 3
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
a)\left\{ \begin{array}{l}
xy - 2x + 3y - 6 = xy\\
xy + 5x - 3y - 15 = xy
\end{array} \right.\\
\to \left\{ \begin{array}{l}
- 2x + 3y = 6\\
5x - 3y = 15
\end{array} \right.\\
\to \left\{ \begin{array}{l}
3x = 21\\
y = \dfrac{{5x - 15}}{3}
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 7\\
y = \dfrac{{20}}{3}
\end{array} \right.\\
b)\left\{ \begin{array}{l}
xy + 8x - 3y - 24 = xy - 54\\
xy - 4x + 2y - 8 = xy + 32
\end{array} \right.\\
\to \left\{ \begin{array}{l}
8x - 3y = - 30\\
- 4x + 2y = 40
\end{array} \right.\\
\to \left\{ \begin{array}{l}
8x - 3y = - 30\\
- 8x + 4y = 80
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = 50\\
x = 15
\end{array} \right.\\
c)\left\{ \begin{array}{l}
xy + \dfrac{3}{4}x - 10y - \dfrac{{15}}{2} = xy\\
xy - \dfrac{1}{2}x + 10y - 5 = xy
\end{array} \right.\\
\to \left\{ \begin{array}{l}
\dfrac{3}{4}x - 10y = \dfrac{{15}}{2}\\
- \dfrac{1}{2}x + 10y = 5
\end{array} \right.\\
\to \left\{ \begin{array}{l}
\dfrac{1}{4}x = \dfrac{{25}}{2}\\
- \dfrac{1}{2}x + 10y = 5
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 50\\
y = 3
\end{array} \right.
\end{array}\)
