MHT CET202618 April 2026Evening ShiftMathematicsDifferential EquationsActual
The differential equation of the family of all parabolas whose axis is the y -axis is
Options
- Ad^2y dx^2 + x dy dx = 0
- Bx d^2y dx^2 - dy dx = 0
- Cd^2y dx^2 - x dy dx = 0
- Dx d^2y dx^2 + dy dx = 0
Correct answer
B. x d^2y dx^2 - dy dx = 0
Step-by-step solution
The equation of the family of all parabolas whose axis is the y -axis is given by: y = ax^2 + c where a and c are arbitrary constants. Differentiating both sides with respect to x , we get: dy dx = 2ax 2a = 1 x dy dx Differentiating again with respect to x , we get: d^2y dx^2 = 2a Substituting the value of 2a from the first derivative into the second derivative, we get: d^2y dx^2 = 1 x dy dx x d^2y dx^2 - dy dx = 0 Answer: x d^2y dx^2 - dy dx = 0