# How do you find the derivative for g(x)= 3tan4x?

The derivative of $\tan \left(u\right)$ is given by $u ' {\sec}^{2} u$.
As $u = 4 x$, then $u ' = 4$
$\frac{\mathrm{dy}}{\mathrm{dx}} = 3 \left(4 {\sec}^{2} \left(4 x\right)\right) = 12 {\sec}^{2} \left(4 x\right)$