Answer
$f′(x)=12x^2\sec^2(x^3)\tan^{3}(x^3)$
Work Step by Step
$f(x)=tan^4(x^3)$
$f′(x)=4tan^{4−1}(x^3)×(\frac{d}{dx})(tan(x^3))$
$f′(x)=4tan^{3}(x^3)×sec^2(x^3)\times(\frac{d}{dx})(x^3)$
$f′(x)=4tan^{3}(x^3)×sec^2(x^3)\times3x^2$
$f′(x)=12x^2\sec^2(x^3)\tan^{3}(x^3)$