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Chapter 4 of 12
Revision Notes

Differentials and Partial Derivatives

Tamil Nadu Board · Class 12 · Mathematics

Quick revision notes for Differentials and Partial Derivatives — Tamil Nadu Board Class 12 Mathematics. Key concepts, formulas, and definitions for last-minute revision.

45 questions26 flashcards5 concepts

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Key Topics to Revise

1

Linear Approximation and Differentials (Single Variable)

  • Linear approximation uses the tangent line to approximate function values near a point
  • The tangent line provides the best linear approximation because the graph appears nearly straight locally
  • Formula: L(x) = f(x₀) + f'(x₀)(x - x₀) represents the tangent line at point x₀
2

Functions of Several Variables: Limits and Continuity

  • Functions of multiple variables map from ℝⁿ to ℝ, producing surfaces (for 2 variables) or hypersurfaces (for 3+ variables)
  • A neighborhood of point (u,v) in ℝ² is an open disc: B_r((u,v)) = {(x,y) : (x-u)² + (y-v)² < r²}
  • For functions of 2+ variables, limit must be the same approaching along ANY path, not just lines
3

Partial Derivatives

  • Partial derivative ∂f/∂x measures rate of change of f with respect to x only, treating y as constant
  • Partial derivative ∂f/∂y measures rate of change of f with respect to y only, treating x as constant
  • Geometrically, ∂f/∂x|(x₀,y₀) is the slope of the tangent line to the curve f(x,y₀) at x = x₀
4

Linear Approximation and Differentials (Multiple Variables)

  • Linear approximation for 2 variables gives equation of tangent plane to surface z = f(x,y)
  • Tangent plane at (x₀,y₀) depends on both partial derivatives: f_x and f_y
  • Differential df = f_x dx + f_y dy represents change along tangent plane

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Full Notes

Key Concepts

Linear approximation is the processThe differential df of a functionWhen approximating valuesPartial derivatives measure the rateFor a function F(x

Frequently Asked Questions

What are the important topics in Differentials and Partial Derivatives for Tamil Nadu Board Class 12 Mathematics?
Key topics in Differentials and Partial Derivatives include Mind map showing the main topics and subtopics covered in the chapter, Step-by-step process for finding and using linear approximation, Worked example showing each step of the linear approximation process. These are the concepts Tamil Nadu Board Class 12 examiners draw on most — study them first, then practise related questions.
How to score full marks in Differentials and Partial Derivatives — Tamil Nadu Board Class 12 Mathematics?
Understand the core concepts first, then work through the 45 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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