Odpowiedź:
[tex]A=(3,1)\ \ \ \ B=(1,-3)\\\\Podstawiamy\ \ wsp\'olrzedne\ \ punkt\'ow\ \ A\ \ i\ \ B\ \ do\ \ wzoru\ \ i\ \ tworzymy\ \ uklad\ \ r\'owna\'n\\\\y=ax+b\\\\\ \ \ \ \begin{cases}1=a\cdot3+b\\-3=a\cdot1+b\end{cases}\\\\\\\begin{cases}1=3a+b\ \ /\cdot(-1)\\-3=a+b\end{cases}\\\\\\+\begin{cases}-1=-3a-b\\-3=a+b\end{cases}\\---------\\-4=-2a\\\\2a=4\ \ /:2\\\\\underline{a=2}[/tex]
[tex]Podstawiamy\ \ warto\'s\'c\ \ a\ \ do\ \ drugiego\ \ r\'ownania\\\\-3=2+b\\\\-3-2=b\\\\-5=b\\\\\underline{b=-5}\\\\\\R\'ownanie\ \ prostej\ \ ma\ \ posta\'c\\\\y=2x+(-5)\\\\\underline{y=2x-5}[/tex]