Question:

For any differentiable function \( y \) of \( x \),
\( \dfrac{d^2 x}{dy^2} \left( \dfrac{dy}{dx} \right)^3 + \dfrac{d^2 y}{dx^2} = \)

Show Hint

Second derivatives of inverse functions satisfy a neat cancellation identity.
Updated On: Mar 23, 2026
  • \(0\)
  • \(y\)
  • \(-y\)
  • x
Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is A

Solution and Explanation


Step 1:
Since \( \dfrac{dx}{dy} = \dfrac{1}{\dfrac{dy}{dx}} \), differentiate w.r.t. \( y \).

Step 2:
Using chain rule:
\( \dfrac{d^2 x}{dy^2} = -\dfrac{d^2 y}{dx^2} \left( \dfrac{dx}{dy} \right)^3 \)
Step 3:
Multiply both sides by \( \left( \dfrac{dy}{dx} \right)^3 \) to get:
\( \dfrac{d^2 x}{dy^2} \left( \dfrac{dy}{dx} \right)^3 + \dfrac{d^2 y}{dx^2} = 0 \)
Was this answer helpful?
0
0