How do you find the derivative of $y = cos(2x)$ ?

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Answer 1 · 2015-12-27T07:27:16

$frac{dy}{dx} = -2sin(2x)$

Let $u = 2x$

$frac{du}{dx} = 2$

$frac{dy}{dx} = frac{d}{dx}(cos(2x))$

$= frac{d}{dx}(cos(u))$

$= frac{d}{du}(cos(u))*frac{du}{dx}$

$= (-sin(u))*(2)$

$= -2sin(2x)$

How do you find the derivative of y = cos(2x) y = cos(2x)?