Odpowiedź:
[tex]a)\\\\\begin{cases}-2x+3y=-13\\5x-2y=38\end{cases}\\\\\\\begin{cases}-2x=-13-3y\ \ /:(-2)\\5x-2y=38\end{cases}\\\\\\\begin{cases}x=\frac{13}{2}+\frac{3}{2}y\\5x-2y=38\end{cases}\\\\\\5(\frac{13}{2}+\frac{3}{2}y)-2y=38\\\\\frac{65}{2}+\frac{15}{2}y-2y=38\ \ /\cdot2\\\\65+15y-4y=76\\\\11y=76-65\\\\11y=11\ \ /:11\\\\y=1[/tex]
[tex]x=\frac{13}{2}+\frac{3}{2}\cdot1=\frac{13}{2}+\frac{3}{2}=\frac{16}{2}=8\\\\\begin{cases}x=8\\y=1\end{cases}[/tex]
[tex]b)\\\\\begin{cases}7x+4y=-11\\-3x+5y=-2\end{cases}\\\\\\\begin{cases}7x=-11-4y\ \ /:7\\-3x+5y=-2\end{cases}\\\\\\\begin{cases}x=-\frac{11}{7}-\frac{4}{7}y\\-3x+5y=-2\end{cases}\\\\\\-3(-\frac{11}{7}-\frac{4}{7}y)+5y=-2\\\\\frac{33}{7}+\frac{12}{7}y+5y=-2\ \ /\cdot7\\\\33+12y+35y=-14\\\\47y=-14-33\\\\47y=-47\ \ /:47\\\\y=-1[/tex]
[tex]x=-\frac{11}{7}-\frac{4}{7}\cdot(-1)=-\frac{11}{7}+\frac{4}{7}=-\frac{7}{7}=-1\\\\\begin{cases}x=-1\\y=-1\end{cases}[/tex]
