[tex]Vectorii\ \vec{a}=u_1\cdot \vec{i}+v_1\cdot \vec{j}\ si\ \vec{b}=u_2\cdot \vec{i}+v_2 \cdot \vec{j}\ sunt\ coliniari\ daca\\
si\ numai\ daca:\boxed{\frac{u_1}{u_2}=\frac{v_1}{v_2}}\\
In\ cazul\ nostru:\\
\frac{-1}{m}=\frac{m}{-4}\\
m^2=4\Rightarrow m\in \{\pm 2\} [/tex]