\[\frac{d}{dx} \cos{(\ln{({x}^{3})})}\]

1
Use Chain Rule on ddxcos(ln(x3))\frac{d}{dx} \cos{(\ln{({x}^{3})})}. Let u=ln(x3)u=\ln{({x}^{3})}. Use Trigonometric Differentiation: the derivative of cosu\cos{u} is sinu-\sin{u}.
sin(ln(x3))(ddxln(x3))-\sin{(\ln{({x}^{3})})}(\frac{d}{dx} \ln{({x}^{3})})

2
Use Chain Rule on ddxln(x3)\frac{d}{dx} \ln{({x}^{3})}. Let u=x3u={x}^{3}. The derivative of lnu\ln{u} is 1u\frac{1}{u}.
sin(ln(x3))×1x3(ddxx3)-\sin{(\ln{({x}^{3})})}\times \frac{1}{{x}^{3}}(\frac{d}{dx} {x}^{3})

3
Use Power Rule: ddxxn=nxn1\frac{d}{dx} {x}^{n}=n{x}^{n-1}.
3sin(ln(x3))x-\frac{3\sin{(\ln{({x}^{3})})}}{x}

Done

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