Odpowiedź:
[tex]b)\\\\\begin{cases}17x+6y=11\ \ /*7\\5x+7y=-2\ \ /*(-6)\end{cases}\\\\\\+\begin{cases}119x+42y=77\\-30x+42y=12\end{cases}\\----------\\89x=89\ \ /:89\\x=1\\\\\\5*1+7y=-2\\\\5+7y=-2\\\\7y=-2-5\\\\7y=-7\ \ /:7\\\\y=-1\\\\\begin{cases}x=1\\y=-1\end{cases}[/tex]
[tex]c)\\\\\begin{cases}-(x+4y)+2=y-x+17\\8x-y=3\end{cases}\\\\\\\begin{cases}-x-4y+2=y-x+17\\8x-y=3\end{cases}\\\\\\\begin{cases}-x-4y-y+x=17-2\\8x-y=3\end{cases}\\\\\\\begin{cases}-5y=15\ \ /:(-5)\\8x-y=3\end{cases}\\\\\\+\begin{cases}y=-3\\8x-y=3\end{cases}\\--------\\8x=0\ \ /:8\\x=0\\\\\begin{cases}x=0\\y=-3\end{cases}[/tex]
