Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Continuity and Differentiability

Question:

If f(x) = sin x, g(x) = x2, h(x) = log x and F(x) = (hogof)(x) then F''(x) is :

Options:

2 cosec3x

2 cot x2 – 4x2cosec2x2

2x cot x2

–2 cosec2x

Correct Answer:

–2 cosec2x

Explanation:

$F(x)= (h o g o f)(x)=h(g(f(x)))$

$=h(g(\sin x))=h\left(\sin ^2 x\right)=\log _e\left(\sin ^2 x\right)$

$=2 \log _e(\sin x)$

$\Rightarrow F'(x) 2 \cot x \Rightarrow f''(x)$ = -2 cosec2x

Hence (4) is correct answer.