Question

\(\dfrac{d}{dx}\!\left(\dfrac{1}{4}\sec4x\right)=\) ?

• A. \(\sec4x\cdot\tan4x\)
• B. \(\sec^{2}4x\)
• C. \(\tan^{2}4x\)
• D. \(\dfrac{1}{16}\sec4x\cdot\tan4x\)

Hint:

For $\sec(kx)$, derivative is $k\,\sec(kx)\tan(kx)$.

Answer 1

The Correct Option is A

\[ \frac{d}{dx}\!\left(\frac14\sec4x\right)=\frac14\cdot (\sec4x\tan4x)\cdot 4=\sec4x\tan4x. \]