Class 12 Maths MCQ – Application of Derivatives

1. The rate of change of a function at a point is given by:

a) Integral of the function
b) Derivative of the function
c) Limit of the function
d) None of the above

Answer:

b) Derivative of the function

Explanation:

Derivative provides the instantaneous rate of change of the function.

2. If y = x^2 + 3x, the rate of change of y with respect to x when x = 2 is:

a) 5
b) 7
c) 3
d) 9

Answer:

b) 7

Explanation:

dy/dx = 2x + 3. At x = 2, dy/dx = 7.

3. A function has a relative maximum at x = c if:

a) f'(c) changes from positive to negative
b) f'(c) changes from negative to positive
c) f'(c) is zero
d) Both a) and c)

Answer:

d) Both a) and c)

Explanation:

Relative maximum occurs when derivative changes from positive to negative.

4. The tangent to the curve at a point (a, f(a)) is:

a) y = f'(a)(x – a) + f(a)
b) y = f(a)(x – a) + f'(a)
c) y = f(a)(x – f(a))
d) None of the above

Answer:

a) y = f'(a)(x – a) + f(a)

Explanation:

The equation represents the tangent line using the point-slope form.

5. The derivative of the function gives:

a) The slope of the tangent to the curve
b) Area under the curve
c) Maximum and minimum values of the function
d) Both a) and c)

Answer:

d) Both a) and c)

Explanation:

Derivative provides the slope as well as conditions for maxima and minima.

6. If a function is increasing in an interval, its derivative in that interval is:

a) Positive
b) Negative
c) Zero
d) Both positive and negative

Answer:

a) Positive

Explanation:

An increasing function has a positive slope or derivative.

7. The normal line to a curve at a point is:

a) Parallel to the tangent
b) Perpendicular to the tangent
c) Coincident with the tangent
d) None of the above

Answer:

b) Perpendicular to the tangent

Explanation:

Normal is always perpendicular to the tangent at the point of contact.

8. The second derivative f''(x) > 0 indicates that the function has a:

a) Relative maximum
b) Relative minimum
c) Point of inflection
d) None of the above

Answer:

b) Relative minimum

Explanation:

Positive second derivative indicates the function is concave upward, hence a minimum.

9. For a projectile thrown upwards, the maximum height is achieved when its velocity is:

a) Maximum
b) Minimum
c) Zero
d) Half of the initial velocity

Answer:

c) Zero

Explanation:

At maximum height, the upward velocity becomes zero before it starts descending.

10. If a company's profit P is given by P(x) where x is the number of items sold, the number of items to be sold to maximize profit is found by:

a) Setting P'(x) = 0
b) Setting P''(x) > 0
c) Both a) and b)
d) None of the above

Answer:

c) Both a) and b)

Explanation:

P'(x) = 0 gives critical points and P''(x) > 0 ensures it's a maximum.

11. Approximation of a function value near a point using derivatives is known as:

a) Taylor's theorem
b) Lagrange's theorem
c) Maclaurin's series
d) Linear approximation

Answer:

d) Linear approximation

Explanation:

Linear approximation uses the tangent line to approximate function values.

12. The derivative of the distance function with respect to time gives:

a) Acceleration
b) Velocity
c) Speed
d) Displacement

Answer:

b) Velocity

Explanation:

Rate of change of distance with respect to time is velocity.

13. For a function f(x) = ax^2 + bx + c, if a > 0, the vertex of the parabola represents:

a) Relative maximum
b) Relative minimum
c) Point of inflection
d) None of the above

Answer:

b) Relative minimum

Explanation:

If a > 0, the parabola opens upwards and the vertex is a minimum point.

14. The value of the derivative at a point of inflection is:

a) Zero
b) Positive
c) Negative
d) Not defined

Answer:

a) Zero

Explanation:

A point of inflection is where the concavity changes, but it doesn't guarantee a zero derivative.

15. The average rate of change of a function over an interval [a, b] is given by:

a) f'(c) for some c in [a, b]
b) (f(b) – f(a))/(b – a)
c) f'(b) – f'(a)
d) None of the above

Answer:

b) (f(b) – f(a))/(b – a)

Explanation:

The average rate is the change in function value divided by the change in the independent variable.

16. The process of determining the maximum or minimum values of a function is called:

a) Differentiation
b) Integration
c) Optimization
d) Normalization

Answer:

c) Optimization

Explanation:

Optimization deals with finding the best values, i.e., maximum or minimum.

17. A function is said to be concave upward in an interval if its:

a) First derivative is increasing
b) First derivative is decreasing
c) Second derivative is positive
d) Second derivative is negative

Answer:

c) Second derivative is positive

Explanation:

Positive second derivative indicates upward concavity.

18. The slope of the secant line between points (a, f(a)) and (b, f(b)) is:

a) (f(b) – f(a))/(b – a)
b) f'(a)
c) f'(b)
d) (f(a) – f(b))/(a – b)

Answer:

a) (f(b) – f(a))/(b – a)

Explanation:

Slope is given by the change in y-values divided by the change in x-values.

19. Rolle's theorem is applicable if:

a) f(a) = f(b)
b) f is continuous on [a, b] and differentiable on (a, b)
c) Both a) and b)
d) Neither a) nor b)

Answer:

c) Both a) and b)

Explanation:

Both conditions must be satisfied for Rolle's theorem.

20. The instantaneous rate of change is given by:

a) Average rate over a small interval
b) First derivative
c) Second derivative
d) Integral of the function

Answer:

b) First derivative

Explanation:

Instantaneous rate of change is represented by the derivative.

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