Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Continuity and Differentiability

Question:

The value of C which satisfies Rolle's Theorem for $f(x)=\sin ^4 x+\cos ^4 x$ in $\left[0, \frac{\pi}{2}\right]$. Then C is:

Options:

$\frac{\pi}{5}$

$\frac{\pi}{3}$

$\frac{\pi}{4}$

$\frac{\pi}{6}$

Correct Answer:

$\frac{\pi}{4}$

Explanation:

The correct answer is Option (3) - $\frac{\pi}{4}$

$f'(x)=\sin^3 x+\cos x-4\cos^3x\sin x=0$

$⇒\sin^2x=\cos^2x$

for $x=\frac{\pi}{4}$ as $x∈[0,\frac{\pi}{2}]$