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Mathematics and Statistics · Class 12 Commerce

Ch 4Applications of Derivatives — Class 12 Mathematics and Statistics, concept-first.

Once we can differentiate a function, the derivative becomes a powerful tool for describing how the function behaves — whether its values are rising or falling, where it turns, and where it reaches a largest or smallest value.

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Key concepts

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Chapter contents

The NCERT structure, section by section. Open a section to see its questions, then read the concept-first solution.

1

Increasing and Decreasing Functions

Once we can differentiate a function, the derivative becomes a powerful tool for describing how the function behaves — whether its values are rising or falling, where it turns, and where it reaches a…

2

Maxima and Minima — The First Derivative Test

A point where a function stops rising and begins to fall (or stops falling and begins to rise) is of special interest: it is where the function attains a local maximum or a local minimum.

3

The Second Derivative Test

The first derivative test works in every case, but it requires checking the sign of on both sides of each critical point.

4

Cost, Revenue and Marginal Analysis

The most direct commercial use of the derivative is marginal analysis — measuring the effect on cost, revenue or profit of producing or selling one more unit.

5

Elasticity of Demand

Demand for a good depends on its price: usually, the higher the price , the smaller the quantity demanded .

6

Optimisation in Commerce — Maximising Profit and Minimising Cost

The techniques of maxima and minima (Sections 2–3) combine with the cost–revenue functions (Section 4) to answer the questions a business most wants answered: what output maximises profit? and what ou…

Exercises

Sample & Board Papers

Sample papers and previous-year board questions for this subject.

+Show 21 questions21 questions
  1. Q1State whether the following statement is true or false. If $f'(x) > 0$ for all $x \in (a, b)$ then $f(x)$ is decreasing function in the inte…Preview
  2. Q2Divide 20 into two ports, so that their product is maximum.Preview
  3. Q3Complete the following activity to find MPC, MPS, APC and APS, if the expenditure $E_c$ of a person with income $I$ is given as: $E_c = (0.0…Preview
  4. Q4A function f is said to be increasing at a point c if ______. (a) $f'(c) = 0$ (b) $f'(c) > 0$ (c) $f'(c) < 0$ (d) $f'(c) = 1$Preview
  5. Q5If $0 < \eta < 1$ then the demand is ______.Preview
  6. Q6For manufacturing x units, labour cost is $150 - 54x$ and processing cost is $x^2$. Price of each unit is $p = 10800 - 4x^2$. Find the value…Preview
  7. Q7For manufacturing x units, labour cost is $150 - 54x$ and processing cost is $x^2$. Price of each unit is $p = 10800 - 4x^2$. Find the value…Preview
  8. Q8A rod of 108 m long is bent to form a rectangle. Find it’s dimensions when it’s area is maximum.Preview
  9. Q9The slope of tangent at any point $(a, b)$ is also called as ______.Preview
  10. Q10Determine the minimum value of the function. $f(x) = 2x^3 - 21x^2 + 36x - 20$Preview
  11. Q11The consumption expenditure $E_c$ of a person with the income $x$. is given by $E_c = 0.0006x^2 + 0.003x$. Find MPC, MPS, APC and APS when t…Preview
  12. Q12The average revenue $R_A$ is 50 and elasticity of demand $\eta$ is 5, the marginal revenue $R_M$ is ______.Preview
  13. Q13Find MPC, MPS, APC and APS, if the expenditure $E_c$ of a person with income I is given as $E_c = (0.0003) I^2 + (0.075) I$ ; When $I = 1000…Preview
  14. Q14Divide the number 84 into two parts such that the product of one part and square of the other is maximum. Solution: Let one part be x then t…Preview
  15. Q15The equation of normal to the curve $y = 3x^2 - x + 1$ at $(1, 3)$ is ______. (a) $x - 5y - 16 = 0$ (b) $x + 5y - 16 = 0$ (c) $x - 5y + 16 =…Preview
  16. Q16If $f(x) = x \cdot \log x$ then its minimum value is ______.Preview
  17. Q17The consumption expenditure $E_c$ of a person with the income $x$. is given by $E_c = 0.0006x^2 + 0.003x$. Find MPC, MPS, APC and APS when t…Preview
  18. Q18If the demand function is $D = 50 - 3p - p^2$. Find the elasticity of demand at $p = 5$ comment on the result.Preview
  19. Q19Find the values of $x$ for which $f(x) = 3x^2 - 15x + 9$ is decreasing.Preview
  20. Q20Find MPC, MPS, APC and APS, if the expenditure $E_c$ of a person with his income $I$ is given as $E_c = (0.0003)I^2 + (0.075)I$, when $I = 1…Preview
  21. Q21A manufacturer can sell $x$ items at a price of ₹$(280 - x)$ each. The cost of producing $x$ items is ₹$(x^2 + 40x + 35)$. Find the number o…Preview

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