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JEE Main Applications of Integration Previous Year Questions With Solutions

JEE Previous year questions and solutions on the Chapter application of integrations are available here. Application of Integrals is applied in various fields like Engineering, Mathematics, Science, etc. In the field of Mathematics, integrals are used to find the areas under curves, arc length of a curve and surface area, areas bounded by a curve, average value of a curve, area between curves, surface area and the volume of geometric solids and many more. Students get to learn the problem-solving method of the questions present in this concept, revolving around the concepts mentioned above, by practicing the application of integral questions provided underneath. We have prepared Chapter wise solutions for the questions asked in past year JEE exams to help students to check their preparation level.

JEE Main Past Year Questions With Solutions on Application of Integrations

Question 1: Find the area of the region A = {(x,y) Є R × R| 0 ≤ x ≤ 3 and 0 ≤ y ≤ 4 and y ≤ x2 + 3}. [area in sq. units]

Solution:

Given: A = {(x,y) Є R × R| 0 ≤ x ≤ 3 and 0 ≤ y ≤ 4 and y ≤ x2 + 3}.

Application of integrals

 

Shaded region be required region. So, from above diagram

Required Region

\(\begin{array}{l}=\int_0^1 (x^2 + 3x) \; dx + (2 \times 4)\end{array} \)
= [(x3/3) + (3x2/2)]+ 8

= 59/6

Question 2: Let S(α) = {(x, y); y2 ≤ x, y2 ≤ α } and, A(α) is area of the region S(α). If for λ, 0 < λ < 4 and A(λ) : A(4) = 2 : 5. Then what will be the value of λ.

Solution:

Let S(α) = {(x, y); y2 ≤ x, y2 ≤ α }

\(\begin{array}{l}A(α) = 2 \int_0^{\alpha} \sqrt{x} \; dx = 2 \alpha^{3/2}\end{array} \)

A(4) = 2 × 43/2 = 16 and A(λ) = 2 × λ3/2

As we know,

A(λ)/A(4) = 2/5

On putting values, we have

=> λ = 4 (4/25)1/3

Question 3: Find the area of the region A = {(x, y) ; y2/2 ≤ x ≤ y + 4}.

Solution:

JEE Main Solution Applications of Integration Previous Year Question

Consider equations from the given inequalities,

y2 = 2x and x – y = 4

Here, y2 = 2x is equation of parabola open towards the +ve x-axis and having focus (1/2, 0)

and x – y = 4, is a straight line.

Solving above equations, we get

y2 = 2(y + 4)

or y2 – 2y – 8 = 0

or y = 4 or y = -2

Therefore, point of intersection of line and curve are (2, -2) and (8, 4).

Required Area

\(\begin{array}{l}=\int_{-2}^4 [(y + 4) – \frac{y^2}{2}]dy\end{array} \)

= [(y2/2) + 4y – (y3/6)]-2 4

= 18 sq. units.

Question 4: Find the area of the region bounded by the curves y = |x + 1| and y = 2x, in the 1st quadrant.

Solution:

Given curves are y = |x + 1| and y = 2x

 

JEE Main Applications of Integration Previous Questions

From diagram,

Required area

\(\begin{array}{l}=\int_0^1[(x + 1) – 2^x] \; dx\end{array} \)
\(\begin{array}{l}=[\frac{x^2}{2} + x – \frac{2^x}{log_e 2}]_0^1\end{array} \)

= 3/2 – 1/loge2

Question 5: Find the value of λ if area bounded by the parabola y2 = 4λx and line y = λx is 1/9. Here λ > 0.

Solution:

Parabola y2 = 4λx and line y = λx

=> (λx)2 = 4λx

=> λ2 x2 = 4λx

Solving above equation ,we get

x = 0 and x = 4/λ

Now, required area is

\(\begin{array}{l}=\int_0^{4/\lambda} (\sqrt{4 \lambda x} – \lambda x) \; dx = 1/9\end{array} \)

JEE Past year questions on Application of derivative

=> 32/3λ – 8/λ = 1/9

=> λ = 24

Therefore, the value of λ is 24. Answer!

Question 6: Find the area bounded by the parabola y = x2 – 1, the tangent at the point (2, 3) to it and the y-axis.

Solution:

JEE Main Applications of Integration Previous Year Questions With Solutions

Equation of parabola y = x2 – 1

Tangent at (2, 3) is (y + 3)/2 = 2x – 1

or y = 4x – 5

From diagram, required area is

= area of triangle formed – ∫-1 3 √(y+1)dy

on solving above expression, we have

Required area = 8/3 sq. units.

Question 7: Find the area (in sq. units) of the region A = {x, y) ; 0 ≤ y ≤ x|x| + 1 and -1 ≤ x ≤ 1}.

Solution:

The required area, A is

\(\begin{array}{l}A = \int_{-1}^0(-x^2 + 1) dx + \int_{0}^1(x^2 +1) dx\end{array} \)
\(\begin{array}{l}=[\frac{-x^3}{3} + x]_{-1}^0 + [\frac{x^3}{3} + x]_{0}^1\end{array} \)

By substituting values, we get

= 2

The required area is 2 sq. units.

Question 8: Find the value of k, if the area enclosed between the curves x = ky2 and y = kx2, k > 0, is one square unit.

Solution:

Given curves are x = ky2 and y = kx2

form given curves, we have

x = k(kx2) 2

=> x = k (k2x4)

=> x = 0 or x3 = (1/k) 3

=> x = 0, 1/k

So, (0, 0) and (1/k, 1/k) are the points of intersection.

Now,

The required area

\(\begin{array}{l}=\int_0^{1/k} (\sqrt{\frac{x}{k}} – kx^2) \; dx = 1\end{array} \)
\(\begin{array}{l}\Rightarrow (\frac{1}{\sqrt k} \times \frac{x^{3/2}}{3/2} – \frac{kx^3}{3})^{1/k}= 1\end{array} \)

=> 2/3k2 – 1/3k2 = 1

=> 1/k2 = 3

=> k2 = 1/3

or k = 1/√3

Question 9: Find the area (in sq. units) bounded by the curve x2 = 4y and the straight-line x = 4y – 2.

Solution:

JEE Main Applications of Integration Previous Question

First find point of intersection between curve and straight line.

x2 = 4y and x = 4y – 2.

=> y = x2/4 and y = (x+2)/4

Solving x2 = x+2

=> x2 – x – 2 = 0

=> (x + 1)(x – 2) = 0

=> x = -1, 2

Now, required area

\(\begin{array}{l}=\int_{-1}^2(\frac{x+2}{4} – \frac{x^2}{4}) \; dx\end{array} \)
\(\begin{array}{l}=\frac{1}{4} \int_{-1}^2 (x + 2 – x^2) \; dx\end{array} \)
\(\begin{array}{l}=\frac{1}{4}[(x^2/2 + 2x – x^3/3)]_{-1}^2\end{array} \)

= 1/4[(6 – 8/3) – (5/6 – 2)]

= 1/4[10/3 + 7/6]

= 9/8

Question 10: What will be the area in the first quadrant bounded by the parabola, y = x2 + 1, the tangent to it at the point (2, 5) and the coordinate axes.

Solution:

JEE Main Previous Year Questions Applications of Integration

 

The equation of tangent is:

(y + 5)/2 = 2x + 1

=> y + 5 = 4x + 2

or y = 4x – 3

Required area =  ∫0 [(x2 + 1) – (1/2) ×( 5/4) × 5

= [(x3/3) + x]0 2  – (25/8)

= 8/3 + 2 – 25/8

= 37/24

Question 11: Find the area of the region bounded by the parabola, y = x2 + 2 and the lines, y = x + 1, x = 0 and x = 3.

Solution:

From the given equations, let us draw the point of intersection and region to find the area.

Applications of Integrals Previous Question

Required area 

\(\begin{array}{l}=\int_0^3(x^2 + 2) – (x + 1) \; dx\end{array} \)
\(\begin{array}{l}=\int_0^3(x^2 – x + 1) \; dx \end{array} \)

= 15/2

Question 12: The area of the region, enclosed by the circle x2 + y2 = 2 which is not common to the region bounded by the parabola y2 = x and the straight line y = x, is

(a) 1/3(12π – 1)

(b) 1/6(12π – 1)

(c) 1/3(6π – 1)

(d) 1/6(24π – 1)

Solution:

Answer: (b)

Explanation:

Applications of Integration Question

 

Required Area = Area of the circle – Area bounded by given line and parabola

= πr2 -∫0 (y – y2) dy

= 2π – [(y2 /2) – (y3/3)]0 (Comparing with the general form of equation of a circle, r = √2)

= 2π – 1/6

= (1/6)(12π – 1) sq. units.

Question 13: Find the area of the region {(x, y) Є R | 4x2 ≤ y ≤ 8x + 12} is

(a) 125/3

(b) 128/3

(c) 124/3

(d) 127/3

Solution:

Answer : (b)

Explanation:

Applications of Integration Previous Year QuestionsFor point of intersection,

4x2 = 8x + 12

or x = 3, -1

Area bounded is given as:

\(\begin{array}{l}A =\int_{-1}^3(8x + 12 – 4x^2) \; dx\end{array} \)
\(\begin{array}{l}=[(8x^2/2) + 12x – 4x^3/3]_{-1}^3\end{array} \)

= 128/3

Question 14: The area bounded by the curve

\(\begin{array}{l}y\le {{x}^{2}}+3x,0\le y\le 4,0\le x\le 3\end{array} \)
is

(a) 59/6

(b) 57/4

(c) 59/3

(d) 57/6

Answer: (a)

Solution:

\(\begin{array}{l}y={{x}^{2}}+3x=4\end{array} \)
\(\begin{array}{l}\Rightarrow {{x}^{2}}+3x=4\end{array} \)
\(\begin{array}{l}\Rightarrow {{x}^{2}}+3x-4=0\Rightarrow x=1\,\,or\,\,x=-4\end{array} \)

Area

\(\begin{array}{l}=\int\limits_{0}^{1}{\left( {{x}^{2}}+3x \right).\,dx+2(4)}\end{array} \)
\(\begin{array}{l}=\left[ \frac{{{x}^{3}}}{3}+\frac{3{{x}^{2}}}{2} \right]_{0}^{1}+2\left( 4 \right)\end{array} \)
\(\begin{array}{l}=\frac{1}{3}+\frac{3}{2}+8=\frac{59}{6}\end{array} \)

Also Check: JEE Main Mathematics Chapter Wise Question Papers

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