COMEDK2016MathematicsParabola
The equation of the parabola with vertex at (-1,1) and focus (2,1) is
Options
- Ay²-2 y-12 x+13=0
- By²-2 y-12 x+11=0
- Cx²+2 x-12 y+13=0
- Dy²-2 y-12 x-11=0
Correct answer
D. y²-2 y-12 x-11=0
Step-by-step solution
Given, vertex of the parabola (h, k)=(-1,1) and its focus is (a+h, k)=(2,1) or a+h=2 a=3 We know that as the y -coordinate of vertex and focus are same,therefore axis of parabola is parallel to X -axis. Thus, equation of parabola is gathered (y-k)²=4 a(x-h) (y-1)²=4 3(x+1) (y-1)²=12 x+12 y²+1-2 y=12 x+12 y²-12 x-2 y-11=0 gathered