Answer
$\frac{\sec^64x}{24}$
Work Step by Step
Find the indefinite integral
$\int sec^64x tan4x dx$
$\int sec^54x sec4xtan4xdx$
Use u-substitution, let $u=sec4x$, $du=4sec4xtan4x$
$\frac{1}{4}\int u^5 du$
$\frac{1}{24}u^6+C$
$\frac{\sec^64x}{24} +C$