a) rownanie prostej
[tex]+\left \{ {{6=-a+b} \atop {-1=a+b}} \right. \\6-1=b+b\\5=2b /:2\\b=\frac52\\\\-1=a+\frac52 /-\frac52\\-\frac22-\frac52=a\\a=-\frac72\\\\y=-\frac72x+\frac52\\y=\frac{-7x+5}2\\y=\frac{-(7x-5)}2\\y=-\frac{7x+5}2[/tex]
b) sprawdzenie wspolliniowosci
[tex]6=-\frac{7*2+5}2\\6=-\frac{14+5}2\\6=-\frac{19}2\\6\neq -9.5\\\text{punkty A, B, C nie sa wspolliniowe}[/tex]
