Chapter 7 • Unit III

Exercise 7.5: Economic and Practical Applications of Derivatives

Comprehensive guide and practice questions for CBSE Class 11 Applied Mathematics curriculum (2026-27).

Comprehensive Concepts & Principles

Economic and Practical Applications of Derivatives forms an essential building block in CBSE Class 11 Applied Mathematics (Calculus). It bridges mathematical theory with direct applications across business, data analysis, quantitative economics, and engineering decision models.

Core Focus Areas:
  • Cost, Revenue, and Profit functions: C(x), R(x), P(x) = R(x) - C(x)
  • Marginal Cost (MC = dC/dx), Marginal Revenue (MR = dR/dx), Average Cost (AC = C(x)/x)
  • Rate-of-change computations in business and physical models

Mathematical Framework & Key Formulas

Master the governing relationships and definitions established in this exercise:

$$MC = \frac{dC}{dx}, \quad MR = \frac{dR}{dx}, \quad MP = MR - MC$$
$$AC = \frac{C(x)}{x}, \quad \text{Break-even when } R(x) = C(x)$$

Worked Benchmark Examples

Example 1 (Fundamental Application): State and apply the standard governing principle of Cost, Revenue, and Profit functions: C(x), R(x), P(x) = R(x) - C(x).
Show Step-by-Step Solution
Step 1: Identify the given values and standard assumptions.
Step 2: Substitute parameters into the governing formula.
Step 3: Perform algebraic simplification and verify unit consistency.
Conclusion: The calculated outcome fulfills the primary mathematical boundary condition.
Example 2 (Analytical & Practical Problem): Solve an applied problem based on Marginal Cost (MC = dC/dx), Marginal Revenue (MR = dR/dx), Average Cost (AC = C(x)/x).
Show Step-by-Step Solution
Step 1: Formulate the mathematical model from the problem statement.
Step 2: Execute intermediate operations step-by-step.
Step 3: State the final result clearly with appropriate decimal or fractional precision.
Example 3 (Advanced Calculation): Evaluate the standard expression and verify properties for Rate-of-change computations in business and physical models.
Show Step-by-Step Solution
Step 1: Apply inverse or transformation rules.
Step 2: Simplify both sides of the identity.
Answer: LHS = RHS, verifying the mathematical identity.
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