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NCERT Solutions · Class 12 · Chapter 5: Continuity and Differentiability

NCERT Solutions for Class 12 Maths Chapter 5 Exercise 5.4

Exercise 5.4: Exponential and logarithmic functions. \((e^x)' = e^x\), \((\log x)' = \tfrac1x\) (x > 0), combined with the chain, product and quotient rules: \((e^{u})' = e^{u}u'\), \((\log u)' = \tfrac{u'}{u}\).

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Exercise 5.4 questions and solutions

Exercise 5.4, Question 1

\(\dfrac{e^x}{\sin x}\)
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  1. Quotient rule: \(\dfrac{e^x\sin x - e^x\cos x}{\sin^2 x}\).
Answer: \(\dfrac{e^x(\sin x - \cos x)}{\sin^2 x}\), \(x \ne n\pi\)

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Exercise 5.4, Question 2

\(e^{\sin^{-1}x}\)
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  1. \[e^{\sin^{-1}x} \cdot \dfrac{1}{\sqrt{1 - x^2}}\]
Answer: \(\dfrac{e^{\sin^{-1}x}}{\sqrt{1 - x^2}}\), \(-1 < x < 1\)

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Exercise 5.4, Question 4

\(\sin(\tan^{-1}e^{-x})\)
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  1. \[\cos(\tan^{-1}e^{-x}) \cdot \dfrac{1}{1 + e^{-2x}} \cdot (-e^{-x})\]
Answer: \[-\dfrac{e^{-x}\cos(\tan^{-1}e^{-x})}{1 + e^{-2x}}\]

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Exercise 5.4, Question 6

\(e^x + e^{x^2} + \dots + e^{x^5}\)
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  1. Term by term: \((e^{x^k})' = kx^{k-1}e^{x^k}\).
Answer: \[e^x + 2xe^{x^2} + 3x^2e^{x^3} + 4x^3e^{x^4} + 5x^4e^{x^5}\]

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Exercise 5.4, Question 7

\(\sqrt{e^{\sqrt x}}\), \(x > 0\)
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  1. \(\sqrt{e^{\sqrt x}} = e^{\sqrt x/2}\), so the derivative is \(e^{\sqrt x/2} \cdot \dfrac{1}{4\sqrt x}\).
Answer: \(\dfrac{\sqrt{e^{\sqrt x}}}{4\sqrt x}\)

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Exercise 5.4, Question 9

\(\dfrac{\cos x}{\log x}\), \(x > 0\)
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  1. Quotient rule: \[\dfrac{-\sin x\log x - \cos x \cdot \frac1x}{(\log x)^2}\]
Answer: \[-\dfrac{x\log x\sin x + \cos x}{x(\log x)^2}\]

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Exercise 5.4, Question 10

\(\cos(\log x + e^x)\), \(x > 0\)
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  1. \[-\sin(\log x + e^x) \cdot \left(\tfrac1x + e^x\right)\]
Answer: \[-\left(\dfrac1x + e^x\right)\sin(\log x + e^x)\]

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Done the NCERT exercises? The board paper asks more

Continuity and Differentiability has 40 original board-style questions (MCQ, assertion–reason, short and long answers, case studies) with step mark schemes, revision notes and a four-step Route to 95. Three sample questions are open to everyone; a free account opens the rest.

Continuity and Differentiability in our sample papers: Sample paper 1 (questions 8, 9, 10, 22, 26) · Sample paper 2 (questions 8, 9, 10, 22, 26) · Sample paper 3 (questions 8, 9, 22, 26, 27) · Sample paper 4 (questions 8, 9, 10, 22, 26) · Sample paper 5 (questions 8, 9, 22, 26, 27).

Also useful: free MCQs and case studies for Continuity and Differentiability · formulas for this chapter (Class 12 formula sheet, free PDF) · official CBSE board and sample papers · our sample papers with marking scheme · the Route to 95 plan

Textbook: NCERT Mathematics Class 12, Parts I and II (rationalised edition, 2023-24 reprint onward), free from ncert.nic.in. Question statements are shortened to the minimum needed; the solutions and tips are our own. CBSE Math Revision is independent and not affiliated with NCERT or CBSE. Spotted a slip? Tell us and it goes in the corrections log.