# How do you find the derivative of y = 3 / (cos2x^2)?

Apr 14, 2017

$\frac{\mathrm{dy}}{\mathrm{dx}} = 12 x \sec \left(2 {x}^{2}\right) \tan \left(2 {x}^{2}\right)$

#### Explanation:

Rewrite the problem as:

$y = 3 \left(\sec \left(2 {x}^{2}\right)\right)$

Now take the derivative. You have to use chain rule for $\sec \left(2 {x}^{2}\right)$

$\frac{\mathrm{dy}}{\mathrm{dx}} = 3 \left(\sec \left(2 {x}^{2}\right)\right) \tan \left(2 {x}^{2}\right) \left(2 {x}^{2}\right) '$

$\frac{\mathrm{dy}}{\mathrm{dx}} = 12 x \sec \left(2 {x}^{2}\right) \tan \left(2 {x}^{2}\right)$