Concept:
Use the section formula in vector form.
Step 1: Write the position vectors.
\[
\vec B=(a,3,2)
\]
\[
\vec C=(-1,4,\beta)
\]
Point \(P\) divides \(BC\) internally in the ratio
\[
(a+1):\beta
\]
Step 2: Apply section formula.
\[
\vec P
=
\frac{(a+1)\vec C+\beta\vec B}{a+\beta+1}
\]
Substituting coordinates,
\[
\vec P
=
\left(
\frac{-(a+1)+a\beta}{a+\beta+1},
\frac{4(a+1)+3\beta}{a+\beta+1},
\frac{\beta(a+1)+2\beta}{a+\beta+1}
\right)
\]
On simplification,
\[
\vec P
=
\left(
-\frac14,\frac{13}{4},\frac94
\right)
\]
Hence,
\[
\boxed{
\left(
-\frac14,\frac{13}{4},\frac94
\right)
}
\]