AP EAMCET202317 May 2023Evening ShiftMathematicsParabolaActual
Let 1 be the directrix of the parabola 9 y^2+12 y+9 x-14=0 and l₁ be the line passing through the vertex of this parabola and the origin. If ( h , k ) is the point of intersection of l and l₁ , then h + k =
Options
- A-9 / 2
- B3 / 2
- C-3 / 4
- D9 / 4
Correct answer
A. -9 / 2
Step-by-step solution
Given: 9 y^2+12 y+9 x-14=0 (y+ 2 3 )^2=-4 1 4 (x-2) Whose vertex is (- 2 3 , 2 ) Equation of line passing through (- 2 3 , 2 ) and (0,0) : (y-0)= 2-0 - 2 3 -0 (x-0) y=-3 x Now, the equation of directrix of parabola (i) is x= 1 4 +2 x= 9 4 ...(iii) Solving eq ^ n (ii) & (iii), we get x= 9 4 and y=- 27 4 h= 9 4 & k=- 27 4 So, h+k= 9 4 - 27 4 = -18 4 = -9 2