Odpowiedź:
[tex]a)\\\\\begin{cases}x-y=4x-3y+5\\x+y=3x+5y-2\end{cases}\\\\\\\begin{cases}x-y-4x+3y=5\\x+y-3x-5y=-2\end{cases}\\\\\\\begin{cases}-3x+2y=5\\-2x-4y=-2\ \ /:2\end{cases}\\\\\\+\begin{cases}-3x+2y=5\\-x-2y=-1\end{cases}\\----------\\-4x=4\ \ /:(-4)\\x=-1\\\\\\-3\cdot(-1)+2y=5\\\\3+2y=5\\\\2y=5-3\\\\2y=2\ \ /:2\\\\y=1\\\\\\\begin{cases}x=-1\\y=1\end{cases}[/tex]
[tex]c)\\\\\begin{cases}\frac{1}{2}(x-y)=\frac{1}{3}(x+y)\\\frac{4}{5}x-\frac{1}{5}(y+3x)=-4\end{cases}\\\\\\\begin{cases}\frac{1}{2}x-\frac{1}{2}y=\frac{1}{3}x+\frac{1}{3}y\ \ /\cdot6\\\frac{4}{5}x-\frac{1}{5}y-\frac{3}{5}x=-4\ \ /\cdot5\end{cases}\\\\\\\begin{cases}3x-3y=2x+2y\\4x-y-3x=-20\end{cases}\\\\\\\begin{cases}3x-3y-2x-2y=0\\x-y=-20\end{cases}\\\\\\\begin{cases}x-5y=0\ \ /\cdot(-1)\\x-y=-20\end{cases}\\\\\\+\begin{cases}-x+5y=0\\x-y=-20\end{cases}\\--------\\4y=-20\ \ /:4\\y=-5[/tex]
[tex]x-(-5)=-20\\\\x+5=-20\\\\x=-20-5\\\\x=-25\\\\\\\begin{cases}x=-25\\y=-5\end{cases}[/tex]
