Question

The equation of the directrix of the parabola $x^2-4 x-3 y+10=0$ is

(a) $y=-\frac{5}{4}$

(b) $y=\frac{5}{4}$

(c) $y=\frac{-3}{4}$

(d) $x=\frac{5}{4}$

Answer 1

SOLUTION — Given equation can be rewritten as

$\begin{aligned} (x-2)^2 & =3(y-2) \\ \text { where }  X^2 & =3 Y, \\ x  =X+2, y=Y+2\end{aligned}$

$\therefore$ Equation of directrix is $Y=-a$

$\Rightarrow \quad y-2=\frac{-3}{4} \Rightarrow y=\frac{5}{4}$

So, The correct option of this question will be (B).