Đáp án:
Giải thích các bước giải:
\(\begin{array}{l}
B1:\\
1.\left\{ \begin{array}{l}
12x - 6y = 9\\
12x - 6y = 10
\end{array} \right. \to \left\{ \begin{array}{l}
0 = 1\left( {voli} \right)\\
12x - 6y = 10
\end{array} \right.
\end{array}\)
⇒Vô nghiệm
\(2.\left\{ \begin{array}{l}
4x + 6y = 10\\
4x + 6y = 10
\end{array} \right. \to \left\{ \begin{array}{l}
0 = 0\left( {ld} \right)\\
4x + 6y = 10
\end{array} \right.\)
⇒ Vô số nghiệm
\(\begin{array}{l}
3.\left\{ \begin{array}{l}
3x - 4y = - 2\\
10x + 4y = 28
\end{array} \right. \to \left\{ \begin{array}{l}
13x = 26\\
3x - 4y = - 2
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 2\\
y = 2
\end{array} \right.\\
4.\left\{ \begin{array}{l}
4x + 10y = 6\\
15x - 10y = 70
\end{array} \right. \to \left\{ \begin{array}{l}
19x = 76\\
4x + 10y = 6
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = 4\\
y = - 1
\end{array} \right.\\
6.\left\{ \begin{array}{l}
y = 5 - 3x\\
0,2x + 0,5 - 0,3x = 0,3
\end{array} \right. \to \left\{ \begin{array}{l}
x = 2\\
y = - 1
\end{array} \right.\\
7.\left\{ \begin{array}{l}
3x - 2y = 0\left( {y \ne 0} \right)\\
x + y = 10
\end{array} \right. \to \left\{ \begin{array}{l}
x = 4\\
y = 6
\end{array} \right.\left( {TM} \right)
\end{array}\)
