UPSC NDA Math Model Paper 5

Here, we have to find the equation of the parabola whose focus is at F(3, 0) and directrix x = - 3.
As we know that, parabola of the form y2=4ax has focus at (a, 0) and equation of directrix is given by x = - a
So, by comparing the focus F(3, 0) and directrix x = - a with (a, 0) and x = - a respectively we get
⇒ a = 3
So, the equation of the required parabola is y2=4⋅3⋅x=12x
Hence, option B is the correct answer.