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dy/dx = −x/y

CAL009 · Calculus · Class 12 + B.Tech

Implicit differentiation

Implicit differentiation differentiates both sides of an equation in x and y, treating y as a function of x, then solves for dy/dx.

📐 Formula

x² + y² = r² ⇒ 2x + 2y dy/dx = 0 ⇒ dy/dx = −x/y

✏️ Worked example

On x² + y² = 25 at (3, 4): dy/dx = −3/4.

🌍 Where it is used

Curves that are not functions, like circles; related rates.

❓ Quick check

For x² + y² = 1, dy/dx at (0, 1)?

🏋️ Practice

Easydy/dx for xy = 1?

Answer: −y/x

MediumSlope of x² + y² = 25 at (4, −3)?

Answer: 4/3

Challengedy/dx for y² = x?

Answer: 1/(2y)