A(m,-3m); B(4,-6); C(6,-1)
prosta AC
\left \{ {{-3m=ma+b} \atop {-1=6a+b}} \right.
\left \{ {{-3m=ma+b} \atop {b=-1-6a}} \right.
\left \{ {{6a-ma=-1-3m} \atop {b=-1-6a}} \right.
\left \{ {{a(6-m)=-1-3m} \atop {b=-1-6a}} \right.
\left \{ {{a=\frac{-1-3m}{6-m}} \atop {b=-1-6a}} \right.
a_1=\frac{-1-3m}{6-m}
prosta BC
\left \{ {{-6=4a+b} \atop {-1=6a+b}} \right.
\left \{ {{b=-6-4a} \atop {-1=6a-6-4a}} \right.
\left \{ {{b=-6-4a} \atop {-1=2a-6}} \right.
\left \{ {{b=-6-4a} \atop {2a-6=-1}} \right.
\left \{ {{b=-6-4a} \atop {2a=-1+6}} \right.
\left \{ {{b=-6-4a} \atop {2a=5}} \right.
\left \{ {{b=-6-4a} \atop {a=2,5}} \right.
a_2=2,5
proste prostopadłe
a_1*a_2=-1
\frac{-1-3m}{6-m}*2,5=-1
(-1-3m)*2,5=-(6-m)
2,5-7,5m=-6+m
-7,5m-m=-6-2,5
-8,5m=-8,5
m=1