Rozwiązanie:
[tex]\textup{4.}[/tex]
[tex]\left\{\begin{array}{ccc}y=-x+8 \ \ \ \ \ \ \ \ \ \ \ \ \\3x+0.5y=10 \ \ \ /\cdot 2\end{array}\right[/tex]
[tex]-\left\{\begin{array}{ccc}y+x=8\\y+6x=20\end{array}\right[/tex]
[tex]-5x=-12\\x=\frac{12}{5}[/tex]
[tex]y=-\frac{12}{5}+8=\frac{28}{5}[/tex]
[tex]\left\{\begin{array}{ccc}x=\frac{12}{5} \\y=\frac{28}{5} \end{array}\right[/tex]
[tex]\textup{5.}[/tex]
[tex]\left\{\begin{array}{ccc}2y=-16x-8 \ \ \ \ \ \ \ \ \\y=-8x-4 \ \ \ / \cdot 2\end{array}\right[/tex]
[tex]-\left\{\begin{array}{ccc}2y+16x=-8\\2y+16x=-8\end{array}\right[/tex]
[tex]0=0 \iff[/tex] tożsamość (nieskończenie wiele rozwiązań)
