[tex]a)\\\\\begin{cases}2x-5y=9\\4x+19y=47 \end{cases}\\\\\begin{cases}2x =5y+9\ \ |:2\\4x+19y=47 \end{cases}\\\\\begin{cases} x =\frac{5}{2}y+ \frac{9}{2} \\4 (\frac{5}{2}y+ \frac{9}{2})+19y=47 \end{cases} \\\\\begin{cases} x =\frac{5}{2}y+ \frac{9}{2} \\10y+18+19y=47 \end{cases} \\\\\begin{cases} x =\frac{5}{2}y+ \frac{9}{2} \\29y =47-18 \end{cases}\\\\ \begin{cases} x =\frac{5}{2}y+ \frac{9}{2} \\29y =29\ \ |:29\end{cases}[/tex]
[tex]\begin{cases} x =\frac{5}{2}*1+ \frac{9}{2} \\y=1 \end{cases}\\\\ \begin{cases} x = \frac{14}{2} \\y=1\end{cases}\\\\ \begin{cases} x =7\\y=1\end{cases}[/tex]
[tex]b) \\\\\begin{cases}x+y=3\\y=3,5-x \end{cases} \\\\\begin{cases}x+3,5-x=3\\y=3,5-x \end{cases} \\\\\begin{cases} 3,5 =3\\y=3,5-x \end{cases}\\\\sprzeczne \, brak\ rozwiazania[/tex]
