If a and b are non-collinear vectors, then the value of α for which the vectors u =(α-2) a + b and v =(2+3 α) a -3 b are collinear is:

If $\displaystyle \vec{a}$ and $\displaystyle \vec{b}$ are non-collinear vectors, then the value of $\displaystyle \alpha$ for which the vectors $$\begin{aligned} & \vec{u}=(\alpha-2) \vec{a}+\vec{b} \text { and } \\ & \vec{v}=(2+3 \alpha) \vec{a}-3 \vec{b} \text { are collinear is: } \end{aligned} $$