Odpowiedź :
[tex]\left \{ {{1=a+b} \atop {5=3a+b}} \right. \\\left \{ {{-3=-3a-3b \atop {5=3a+b\\}\\} \right.\\ \\2=-2b\\b=-1\\\\1=a-1\\a=2\\\\f(x)=2x-1\\\\-2=2*\frac{-1}{2}-1\\ -2=-1-1\\-2=-2\\\\[/tex]
Punkt C należy do prostej
[tex]\left \{ {{1=a+b} \atop {5=3a+b}} \right. \\\left \{ {{-3=-3a-3b \atop {5=3a+b\\}\\} \right.\\ \\2=-2b\\b=-1\\\\1=a-1\\a=2\\\\f(x)=2x-1\\\\-2=2*\frac{-1}{2}-1\\ -2=-1-1\\-2=-2\\\\[/tex]
Punkt C należy do prostej