Highly selective Backlog Qs for JEE MainMathematicsParabola
The equation of the parabola with the focus (3,0) and the directrix x+3=0 , is.
Options
- Ay^2=3 x
- By^2=6 x
- Cy^2=12 x
- Dy^2=2 x
Correct answer
C. y^2=12 x
Step-by-step solution
Given that focus is S(3,0) , let P(x, y) be any point on the parabola. Directrix is, x+3=0 Also, S P^2=P M^2 aligned & (x-3)^2+(y-0)^2= ( x+3 1 )^2 & (x-3)^2+y^2=(x+3)^2 & y^2=(x+3)^2-(x-3)^2 & =(x+3+x-3)(x+3-x+3) & y^2=2 x 6=12 x aligned