Explanation
Given: Points with position vectors
ai^+10j+13k^,6i+11j+11k^ and 29j^+βj^−8k^ are collinear.
So,
6−29α−6=11−β10−11=11+813−11
⇒32(α−6)=11−β−1=192
⇒32(α−6)=192
\begin{aligned}
& \Rightarrow19\alpha-114=3\Rightarrow19\alpha=117 \\
& \Rightarrow\alpha=\frac{117}{19} \\
& \mathrm{And},\frac{-1}{11-\beta}=\frac{2}{19} \\
& \Rightarrow-19=22-2\beta \\
& \Rightarrow2\beta=41 \\
& \Rightarrow\beta=\frac{41}{2} \\
& \therefore\left(19\alpha-6\beta\right)^2=\left(19\times\frac{117}{19}-\frac{6\times41}{2}\right)^2 \\
& =(117-123)^{2}=36
\end{aligned}