Question
Differentiate the following functions with respect to x:

$\frac{\text{x}\tan\text{x}}{\sec\text{x}+\tan\text{x}}$

Answer

We have, 

$\frac{\text{d}}{\text{dx}}\Big(\frac{\text{x}\tan\text{x}}{\sec\text{x}+\tan\text{x}}\Big)$

Using Quotient rule, we get 

$=\frac{(\sec\text{x}+\tan\text{x})\frac{\text{d}}{\text{dx}}(\text{x}\tan\text{x})-(\text{x}\tan\text{x})\frac{\text{d}}{\text{dx}}(\sec\text{x}+\tan\text{x}){}}{(\sec\text{x}+\tan\text{x})^2}$

$=\frac{(\sec\text{x}+\tan\text{x})(\text{x}\sec^2\text{x}+\tan\text{x})-(\text{x}\tan\text{x})(\sec\text{x}\tan\text{x}+\sec^2\text{x})}{(\sec\text{x}+\tan\text{x})^2}$ [Used product rule]

$=\frac{(\sec\text{x}+\tan\text{x})(\text{x}\sec^2\text{x}+\tan\text{x})-\text{x}\sec\text{x}+\tan^2\text{x}-\text{x}\tan\text{x}\sec^2\text{x})}{(\sec\text{x}+\tan\text{x})^2}$

$=\frac{(\sec\text{x}+\tan\text{x})(\text{x}\sec^2\text{x}+\tan\text{x})-(\text{x}\tan\text{x})(\sec\text{x}\tan\text{x}+\sec^2\text{x})}{(\sec\text{x}+\tan\text{x})^2}$

$=\frac{(\sec\text{x}+\tan\text{x})(\text{x}\sec^2\text{x}+\tan\text{x})-\text{x}\tan\text{x}\sec\text{x}(\sec\text{x}+\tan\text{x})}{(\sec\text{x}+\tan\text{x})^2}$

$=\frac{(\text{x}\sec^2\text{x}+\tan\text{x}-\text{x}\tan\text{x}\sec\text{x})(\sec\text{x}+\tan\text{x})}{(\sec\text{x}+\tan\text{x})^2}$

$=\frac{(\text{x}\sec^2\text{x}+\tan\text{x}-\text{x}\tan\text{x}\sec\text{x})}{(\sec\text{x}+\tan\text{x})}$

$=\frac{\text{x}\sec\text{x}(\sec\text{x}-\tan\text{x})+\tan\text{x}}{(\sec\text{x}+\tan\text{x})}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free