Answer
$\sec^2[\ln(ax+b)]*\frac{a}{ax+b}$
Work Step by Step
$\frac{d}{dx}\tan[\ln(ax+b)]$
$=\sec^2[\ln(ax+b)]*\frac{d}{dx}\ln(ax+b)$
$=\sec^2[\ln(ax+b)]*\frac{1}{ax+b}*\frac{d}{dx}(ax+b)$
$=\sec^2[\ln(ax+b)]*\frac{1}{ax+b}*a$
$=\sec^2[\ln(ax+b)]*\frac{a}{ax+b}$