## Calculus 10th Edition

$u=\pi x^2$ $y=3\tan{u}$
Working from the inside out: Take $x$; square it and multiply it by $\pi\leftarrow$ "inner function." Take $\pi x^2$; take the tangent of it and multiply it by $3\leftarrow$ "outer function." $u=\pi x^2$ $y=3\tan{u}$