NCERT Class 12 Maths · Chapter 5 Continuity And Differentiability · Exercise 5.7 Question 6
Find the second derivative of \(e^{x} \sin{\left(5 x \right)}\) with respect to x; on R.
💡 Concept Hints
Identify the domain and the inner and outer functions, or the relevant one-sided limits.
Apply the appropriate differentiation or limit rule, keep all chain factors, and check exceptional points.
✅ Step-by-Step Solution
Final Answer: \(2 \left(- 12 \sin{\left(5 x \right)} + 5 \cos{\left(5 x \right)}\right) e^{x}\)
Work on R.
Product rule: differentiate each variable factor once, keeping the other factors unchanged. Here \(\frac{d}{d x} e^{x} \sin{\left(5 x \right)}\) = \(e^{x} \sin{\left(5 x \right)} + 5 e^{x} \cos{\left(5 x \right)}\).
Differentiate the first derivative \(e^{x} \sin{\left(5 x \right)} + 5 e^{x} \cos{\left(5 x \right)}\) again.
Product rule: differentiate each variable factor once, keeping the other factors unchanged. Here \(\frac{d}{d x} e^{x} \sin{\left(5 x \right)}\) = \(e^{x} \sin{\left(5 x \right)} + 5 e^{x} \cos{\left(5 x \right)}\).
Product rule: differentiate each variable factor once, keeping the other factors unchanged. Here \(\frac{d}{d x} 5 e^{x} \cos{\left(5 x \right)}\) = \(- 25 e^{x} \sin{\left(5 x \right)} + 5 e^{x} \cos{\left(5 x \right)}\).
Sum rule: \(\frac{d}{d x} \left(e^{x} \sin{\left(5 x \right)} + 5 e^{x} \cos{\left(5 x \right)}\right)\) = \(- 24 e^{x} \sin{\left(5 x \right)} + 10 e^{x} \cos{\left(5 x \right)}\).
Combining the terms gives y″ = \(2 \left(- 12 \sin{\left(5 x \right)} + 5 \cos{\left(5 x \right)}\right) e^{x}\).
Master Chapter 5: Continuity And Differentiability
Practise interactive questions, flashcards, visual mind maps, and timed board tests for Continuity And Differentiability.