Question 23
If the three points
$$
\begin{aligned}
& (1, a, b) \\
& (a, 2, b) \\
& (a, b, 3)
\end{aligned}
$$
are collinear (in 3-space), what is the value of $a+b$?
$$
\begin{aligned}
& (1, a, b) \\
& (a, 2, b) \\
& (a, b, 3)
\end{aligned}
$$
are collinear (in 3-space), what is the value of $a+b$?