Question
The determinant \[\left| {\begin{array}{*{20}{c}}
{xp + y}&x&y \\
{yp + z}&y&z \\
0&{xp + y}&{yp + z}
\end{array}} \right| = 0\] for all $$p \in R$$ if
A.
$$x, y, z$$ are in A.P.
B.
$$x, y, z$$ are in G.P.
C.
$$x, y, z$$ are in H.P.
D.
$$xy, yz, zx$$ are in A.P.
Answer :
$$x, y, z$$ are in G.P.
Solution :
Using $${C_1} \to {C_1} - p \times {C_2} - {C_3},$$ we get $$\left( {x{p^2} - z} \right)\left( {xz - {y^2}} \right) = 0.$$
For all $$p,x{p^2} - z \ne 0.\,{\text{So, }}{y^2} = xz.$$