Question

If $P_r=(x_r,y_r);r=1,2,3;$ are three points on the parabola $x^2=8y$, where $x_1,x_2,x_3$ are in GP, then $y_1,y_2,y_3$ are in

• A. AP
• B. GP
• C. HP
• D. none of these

Answer 1

Answer: (B)

GP

Given $(x_r,y_r)$ lie on the parabola $x^2=8y$
Therefore $y_1=\frac{x_1^2}{8},y_2=\frac{x_2^2}{8}$ and $y_3=\frac{x_3^2}{8}$
Also given $x_1,x_2,x_3$ are in G.P
Hence, $y_1,y_2,y_3$ are also in G.P