Problem of the Week

Updated at Feb 8, 2016 8:57 AM

How can we find the derivative of 7x−tan⁡x7x-\tan{x}?

Below is the solution.



ddx7x−tan⁡x\frac{d}{dx} 7x-\tan{x}

1
Use Sum Rule: ddxf(x)+g(x)=(ddxf(x))+(ddxg(x))\frac{d}{dx} f(x)+g(x)=(\frac{d}{dx} f(x))+(\frac{d}{dx} g(x)).
(ddx7x)−(ddxtan⁡x)(\frac{d}{dx} 7x)-(\frac{d}{dx} \tan{x})

2
Use Power Rule: ddxxn=nxn−1\frac{d}{dx} {x}^{n}=n{x}^{n-1}.
7−(ddxtan⁡x)7-(\frac{d}{dx} \tan{x})

3
Use Trigonometric Differentiation: the derivative of tan⁡x\tan{x} is sec⁡2x\sec^{2}x.
7−sec⁡2x7-\sec^{2}x

Done
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