Conditia ca A(x1, y1), B(x2, y2), C(x3, y3) sa fie coliniare este ca
[tex] det\left[\begin{array}{ccc}x1&y1&1\\x2&y2&1\\x3&y3&3\end{array}\right]=0 [/tex].
In cazul nostru vom avea:
[tex] det \left[\begin{array}{ccc}-1&6&1\\m&3&1\\5&0&1\end{array}\right]=0 [/tex]
<=> -3+0+30-15-0-6m=0 <=>12-6m=0 <=> m=2
