# Thread: Implicit Differentiation

1. ## Implicit Differentiation

I am really confused on how to differentiate things like this.. please help.

6y^3 + 5xsiny = cos3x

find dy/dx.

2. Originally Posted by mmfoxall
I am really confused on how to differentiate things like this.. please help.

6y^3 + 5xsiny = cos3x

find dy/dx.
$\displaystyle \displaystyle 18y^2 \cdot \frac{dy}{dx} + 5x \cdot \cos{y} \cdot \frac{dy}{dx} + 5\sin{y} = -3\sin(3x)$

solve for $\displaystyle \displaystyle \frac{dy}{dx}$

3. What i get is [-3sin(3x) - 5sin(y)]/[(18y^2 + 5xcos(y)]. Is this right?

4. Originally Posted by mmfoxall
What i get is [-3sin(3x) - 5sin(y)]/[(18y^2 + 5xcos(y)]. Is this right?

Correct!