Odpowiedź:
[tex]a)\\\\\begin{cases}x+2y=6\\3x+6y=18\ \ /:(3)\end{cases}\\\\\\+\begin{cases}x+2y=6\\-x-2y=-6\end{cases}\\---------\\0=0\\\\Uklad\ \ r\'owna\'n\ \ nieoznaczony\\\\\\b)\\\\\begin{cases}x+4y=12\ \ /\cdot2\\-2x+y=10\end{cases}\\\\\\+\begin{cases}2x+8y=24\\-2x+y=10\end{cases}\\---------\\9y=34\ \ /:9\\\\y=\frac{34}{9}\\\\\\-2x+\frac{34}{9}=10\\\\-2x=10-\frac{34}{9}\\\\-2x=\frac{90}{9}-\frac{34}{9}\\\\-2x=\frac{56}{9}\ \ /:(-2)\\\\x=-\frac{\not56^2^8}{9}\cdot\frac{1}{\not2_{1}}\\\\x=-\frac{28}{9}[/tex]
[tex]\begin{cases}x=-\frac{28}{9}\\y=\frac{34}{9}\end{cases}\\\\\\Uklad\ \ r\'owna\'n\ \ oznaczony\\\\\\c)\\\\\begin{cases}3x+y=10\ \ /\cdot(-2)\\6x+2y=13\end{cases}\\\\\\\+\begin{cases}-6x-2y=-20\\6x+2y=13\end{cases}\\--------\\0=-7\\\\Uklad\ \ r\'owna\'n\ \ sprzeczny[/tex]
