AP EAMCET2014MathematicsDifferential Equations
The differential equation of the family of parabolas with vertex at (0,-1) and having axis along the Y -axis is
Options
- Ay y^ +2 x y+1=0
- Bx y^ +y+1=0
- Cx y^ -2 y-2=0
- Dx y^ -y-1=0
Correct answer
C. x y^ -2 y-2=0
Step-by-step solution
Equation of family of parabola having vertex (0,-1) and axis along y -axis is x^2=4 a(y+1) On differentiating both sides w.r.t. x , we get 2 x=4 a y^ a= x 2 y^ On putting a= 1 2 y^ in Eq. (i), we get array cc & x^2=4 x 2 y^ (y+1) & x= 2 y^ (y+1) & x y^ -2 y-2=0 array