Question

Find dy/dx : x²+ xy + y² = 100

Answer 1

Answer:

$2x + x \frac{dy}{dx} + 2y \frac{dy}{dx} = 0 \\ \\ \frac{dy}{dx} (x + 2y) = - 2x \\ \\ \frac{dy}{dx} = - \frac{2x}{x + 2y}$

Answer 2

Answer:

y'=-(2x+y)/(x+2y)=dy/dx