Odpowiedź:
[tex]b)\\\\\begin{cases}3x-5y=7\ \ /\cdot2\\4x+2y=3\ \ /\cdot5\end{cases}\\\\\\+\begin{cases}6x-10y=14\\20x+10y=15\end{cases}\\----------\\26x=29\ \ /:26\\\\x=\frac{29}{26}\\\\\\\not4^2\cdot\frac{29}{\not26_{13}}+2y=3\\\\\frac{58}{13}+2y=3\\\\2y=3-\frac{58}{13}\\\\2y=\frac{39}{13}-\frac{58}{13}\\\\2y=-\frac{19}{13}\ \ /:2\\\\y=-\frac{19}{13}\cdot\frac{1}{2}\\\\y=-\frac{19}{26}\\\\\begin{cases}x=\frac{29}{26}\\y=-\frac{19}{26}\end{cases}[/tex]
[tex]c)\\\\\begin{cases}6x+5y=4\ \ /\cdot2\\-5x-2y=3\ \ /\cdot5\end{cases}\\\\\\+\begin{cases}12x+10y=8\\-25x-10y=15\end{cases}\\----------\\-13x=23\ \ /:(-13)\\\\x=-\frac{23}{13}\\\\\\-5\cdot(-\frac{23}{13})-2y=3\\\\\frac{115}{13}-2y=3\\\\-2y=3-\frac{115}{13}\\\\-2y=\frac{39}{13}-\frac{115}{13}\\\\-2y=-\frac{76}{13}\ \ /:(-2)\\\\y=\frac{76}{13}:2\\\\y=\frac{\not76^3^8}{13}\cdot\frac{1}{\not2_{1}}\\\\y=\frac{38}{13}\\\\\begin{cases}x=-\frac{23}{13}\\y=\frac{38}{13}\end{cases}[/tex]
[tex]d)\\\\\begin{cases}3x-2y=-9\ \ /\cdot5\\4x+5y=-9\ \ /\cdot2\end{cases}\\\\\\+\begin{cases}15x-10y=-45\\8x+10y=-18\end{cases}\\----------\\23x=-63\ \ /:23\\\\x=-\frac{63}{23}\\\\\\3\cdot(-\frac{63}{23})-2y=-9\\\\-\frac{189}{23}-2y=-9\\\\-2y=-9+\frac{189}{23}\\\\-2y=-\frac{207}{23}+\frac{189}{23}\\\\-2y=-\frac{18}{23}\ \ /:(-2)\\\\y=\frac{18}{23}:2\\\\y=\frac{\not18^9}{23}\cdot\frac{1}{\not2_{1}}\\\\y=\frac{9}{23}\\\\\begin{cases}x=-\frac{63}{23}\\y=\frac{9}{23}\end{cases}[/tex]
