📐 Mathematics · Class 12 · JEE
Application of Derivatives - Practice Questions with Answers 68 free MCQs on Application of Derivatives, each with its own worked answer and explanation. Use derivatives to study rate of change, increasing and decreasing functions, tangents and normals, and maxima and minima, with classic optimization problems.
Take the timed Application of Derivatives chapterwise test → 68 practice questions on Application of Derivatives , sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Application of Derivatives notes .
Tangent and Normal at a Point on a Curve (a,b) tangent (slope=f'(a)) normal (slope=-1/f'(a)) Tangent and normal are always perpendicular to each other at the point of contact The tangent at a point touches the curve with slope f'(a); the normal is the line perpendicular to the tangent at that same point, with slope -1/f'(a) - together they describe the curve's local direction and the line "straight into" the curve.
Easy - 20 questions Q1.
If f'(x) > 0 for all x in an interval, the function f is:
A Strictly decreasingB Strictly increasingC ConstantD UndefinedShow answer & explanation →
Q2.
If f'(x) < 0 for all x in an interval, the function f is:
A Strictly increasingB ConstantC Strictly decreasingD Has a maximumShow answer & explanation →
Q3.
A critical point of a function f is a point where:
A f(x) = 0, meaning the function itself vanishesB f'(x) = 0 or f'(x) does not existC f''(x) = 0 always, marking a guaranteed inflection pointD f is discontinuous at that particular x-valueShow answer & explanation →
Q4.
The slope of the tangent to the curve y = f(x) at point (x<sub>1</sub>, y<sub>1</sub>) is given by:
A f(x<sub>1</sub>)B f'(x<sub>1</sub>)C -1/f'(x<sub>1</sub>)D f''(x<sub>1</sub>)Show answer & explanation →
Q7.
By the second derivative test, if f'(c) = 0 and f''(c) > 0, then x = c is a:
A Local maximumB Local minimumC Point of inflectionD DiscontinuityShow answer & explanation →
Q8.
By the second derivative test, if f'(c) = 0 and f''(c) < 0, then x = c is a:
A Local minimumB Local maximumC Saddle pointD Undefined pointShow answer & explanation →
Q10.
If Area of a circle A = pi r<sup>2</sup>, then dA/dt in terms of dr/dt is:
A pi r (dr/dt)B 2 pi r (dr/dt)C pi r<sup>2</sup> (dr/dt)D 2 pi (dr/dt)Show answer & explanation →
Q11.
Rolle's theorem requires which of the following conditions on [a, b]?
A f(a) = f(b)B f(a) = -f(b)C f'(a) = f'(b)D f(a) and f(b) have opposite signsShow answer & explanation →
Q12.
The Mean Value Theorem guarantees a point c in (a, b) where f'(c) equals:
A f(b) + f(a), the sum of endpoint valuesB [f(b) - f(a)] / (b - a)C f(a) / f(b), the ratio of endpoint valuesD (a + b) / 2, the midpoint of the intervalShow answer & explanation →
Q13.
Using the approximation formula, f(x + dx) is approximately equal to:
A f(x) - f'(x) dxB f(x) + f'(x) dxC f'(x) + f(x) dxD f(x) times f'(x) dxShow answer & explanation →
Q14.
The derivative dy/dx represents the ___ of a function:
A rate of changeB total areaC enclosed volumeD definite integralShow answer & explanation →
Q16.
At a point of local maximum or minimum, the first derivative f′(x) is:
A zeroB always positiveC always negativeD infiniteShow answer & explanation →
Q17.
A function is increasing on an interval where its derivative f′(x) is:
A positiveB negativeC zeroD undefinedShow answer & explanation →
Q19.
The second derivative f″(x) is used to determine the ___ of a curve:
A concavityB total lengthC colourD domainShow answer & explanation →
Medium - 20 questions Q21.
Find the equation of the tangent to the curve y = x<sup>2</sup> at the point (2, 4).
A y = 4x - 4B y = 2xC y = 4x + 4D y = 2x - 4Show answer & explanation →
Q22.
Find the equation of the normal to the curve y = x<sup>3</sup> at the point (1, 1).
A y = 3x - 2B y - 1 = -(1/3)(x - 1)C y = -3x + 4D y - 1 = 3(x - 1)Show answer & explanation →
Q23.
Find the interval in which f(x) = x<sup>2</sup> - 4x + 3 is strictly decreasing.
A x > 2B x < 2C x < -2D All real xShow answer & explanation →
Q24.
Find the critical points of f(x) = x<sup>3</sup> - 3x.
A x = 0, treated as the sole critical pointB x = 1 and x = -1C x = 3, treated as the sole critical pointD x = -3 and x = 3, an incorrect pair of rootsShow answer & explanation →
Q25.
For f(x) = x<sup>3</sup> - 6x<sup>2</sup> + 9x + 1, the local maximum occurs at:
A x = 1B x = 3C x = 0D x = 2Show answer & explanation →
Q29.
The radius of a sphere is increasing at the rate of 2 cm/s. Find the rate of increase of its volume when the radius is 5 cm.
A 50 pi cm<sup>3</sup>/sB 200 pi cm<sup>3</sup>/sC 100 pi cm<sup>3</sup>/sD 20 pi cm<sup>3</sup>/sShow answer & explanation →
Q30.
Find the point on the curve y = x<sup>2</sup> where the tangent is parallel to the line y = 4x - 5.
A (1, 1)B (2, 4)C (4, 16)D (0, 0)Show answer & explanation →
Q31.
Verify Rolle's theorem for f(x) = x<sup>2</sup> - 4x + 3 on [1, 3]. The value of c satisfying f'(c) = 0 is:
A c = 1B c = 1.5C c = 2D c = 3Show answer & explanation →
Q32.
Find c using the Mean Value Theorem for f(x) = x<sup>2</sup> on the interval [1, 4].
A c = 2B c = 2.5C c = 3D c = 3.5Show answer & explanation →
Q33.
A balloon's volume increases such that its radius increases at 3 cm/s. Find the rate of change of surface area when r = 4 cm. (Surface area = 4 pi r<sup>2</sup>)
A 48 pi cm<sup>2</sup>/sB 64 pi cm<sup>2</sup>/sC 96 pi cm<sup>2</sup>/sD 32 pi cm<sup>2</sup>/sShow answer & explanation →
Q34.
By the second-derivative test, if f′(x) = 0 and f″(x) > 0, the point is a local:
A minimumB maximumC point of inflectionD saddleShow answer & explanation →
Q36.
The equation of the tangent to y = f(x) at (x₁, y₁) is y − y₁ =:
A f′(x₁)·(x − x₁)B just f(x₁)C always simply 0D just x − x₁Show answer & explanation →
Q38.
For a sphere of volume V = (4/3)πr³, the rate of change of volume with respect to r is:
A 4πr²B πr²C (4/3)πr²D 2πrShow answer & explanation →
Q39.
The slope of the normal to a curve is the ___ of the tangent’s slope:
A the negative reciprocalB exactly the same valueC twice as large a valueD the square of itShow answer & explanation →
Hard - 28 questions Q41.
Show that among all rectangles with a given perimeter of 40 units, the one with maximum area is a square. What is the maximum area?
A 80 sq unitsB 100 sq unitsC 120 sq unitsD 200 sq unitsShow answer & explanation →
Q42.
An open box is to be made from a square sheet of side 12 cm by cutting equal squares of side x from each corner and folding up the sides. Find x that maximizes the volume.
A x = 1B x = 2C x = 3D x = 4Show answer & explanation →
Q43.
Find two positive numbers x and y such that x + y = 10 and x<sup>2</sup> + y<sup>2</sup> is minimum. Find this minimum value.
Show answer & explanation →
Q44.
Among all closed cylindrical cans of a fixed volume V, the surface area is minimized when the height h and radius r satisfy:
A h = rB h = 2rC h = 3rD h = r/2Show answer & explanation →
Q45.
A man of height 2 m walks away from a lamp post of height 6 m at a speed of 1.5 m/s. Find the rate at which the length of his shadow increases.
A 0.5 m/sB 0.75 m/sC 1 m/sD 1.5 m/sShow answer & explanation →
Q46.
Find the maximum value of the function f(x) = -2x<sup>3</sup> + 3x<sup>2</sup> + 12x - 5 on the interval [-2, 3].
A At x = -1, value 5B At x = 2, value 15C At x = 3, value 4D At x = -2, value -1Show answer & explanation →
Q47.
A wire of length 36 m is to be cut into two pieces. One piece (length 4x) is bent into a square of side x, and the other into a circle of radius r. To minimize the total area enclosed, what relation must hold between x and r?
A x = rB x = 2rC x = 3rD x = r/2Show answer & explanation →
Q48.
Verify the Mean Value Theorem for f(x) = x<sup>3</sup> - 5x<sup>2</sup> - 3x on [1, 3]. Find the value of c in (1, 3) satisfying the theorem.
A c = 7/3B c = 1C c = 8/3D c = 5/3Show answer & explanation →
Q49.
The sum of the surface areas of a cube and a sphere is constant. Show that the sum of their volumes is minimum when the edge of the cube equals the diameter of the sphere. If the cube's edge is a and sphere's radius is r at the minimum, what is the relationship?
A a = rB a = 2rC a = 3rD a = r/2Show answer & explanation →
Q50.
Find the maximum area of an isosceles triangle inscribed in a circle of radius r, with the triangle's apex at the top of a vertical diameter.
A (3 sqrt(3)/4) r<sup>2</sup>B (sqrt(3)/4) r<sup>2</sup>C (3/2) r<sup>2</sup>D (sqrt(3)/2) r<sup>2</sup>Show answer & explanation →
Q51.
A point moves along the curve y = x<sup>3</sup> - 3x. Find the points where the tangent to the curve is parallel to the x-axis, and classify them.
A (1,-2) is local min, (-1,2) is local maxB (1,-2) is local max, (-1,2) is local minC Both are inflection pointsD (0,0) is the only such pointShow answer & explanation →
Q54.
Among all rectangles of a fixed perimeter, the area is greatest when the rectangle is a:
A squareB long thin oneC triangleD circleShow answer & explanation →
Q56.
The point where a curve changes its concavity is called a point of:
A inflectionB maximumC minimumD tangencyShow answer & explanation →
Q57.
If f′(x) > 0 for every x in an interval, the function is:
A strictly increasingB strictly decreasingC constantD periodicShow answer & explanation →
Q58.
The derivative of the position of a particle with respect to time gives its:
A velocityB accelerationC displacementD distanceShow answer & explanation →
Q59.
The second derivative of position with respect to time gives the:
A accelerationB velocityC displacementD speedShow answer & explanation →
Q65.
A spherical balloon's volume increases at 100 cm³/s. When the radius is 5 cm, the radius increases at:
A 1/π cm/sB 1/(2π) cm/sC 1/(4π) cm/sD π cm/sShow answer & explanation →