The area (in sq. units) of the region (x, y): 0 ≤ y ≤ 2|x| + 1, 0 ≤ y ≤ x² + 1, |x| ≤ 3 is

Solution & Explanation

Related Formula

Area under a curve using definite integration bounded by curves:

Area = 2 ∫ₐ^b f(x) dx
Core Logic

Since both bounding graphs are symmetric about the y-axis, we can integrate over the positive domain (x ≥ 0) and double the result:

Area Bounded by Curves and Absolute Value Functions diagram for Q70 - JEE Main 2025 Morning
Area Bounded by Curves and Absolute Value Functions diagram for Q70 - JEE Main 2025 Morning
Intersecting points: x² + 1 = 2x + 1 x = 2.

Step 1: Setting Up the Bound Segments

The region splits into two integral segments based on which curve sits lower: Segment 1: From 0 to 2, bounded by the parabola y = x² + 1. Segment 2: From 2 to 3, bounded by the straight line y = 2x + 1.

Step 2: Performing Integration
$Area = 2 [ ∫₀² (x² + 1) dx + ∫₂³ (2x + 1) dx ]= 2 [ ( (8)/(3) + 2 ) + (9 + 3 - 4 - 2) ] = 2 [ (14)/(3) + 6 ] = (64)/(3)$
Pattern Recognition

Exploiting structural symmetry drops the integration limits, avoiding messy sign evaluations with absolute terms.

Chapter Mix

Class 12 Maths: Area Under Curves

More Area Under Curves Previous-Year Questions — Page 5

Q jee_main_2024_29_january_evening Area Under Curves
Let the area of the region (x,y):0≤ x≤ 3,0≤ y≤ x² +2,2x + 2 be A. Then 12A is equal to
Numerical Answer. Answer: 164 to 164

Solution

Related Formula
Area A = ∫ f(x), g(x) dx
Core Logic

Let us find the point of intersection of the curves y = x² + 2 and y = 2x + 2:

x² + 2 = 2x + 2 x² - 2x = 0 x = 0 or x = 2

Evaluating behaviors over boundaries:

  • For 0 ≤ x ≤ 2: x² + 2 ≤ 2x + 2 = x² + 2
  • For 2 ≤ x ≤ 3: 2x + 2 ≤ x² + 2 = 2x + 2
Step 1: Integration Resolution

Setting up continuous area integral steps:

A = ∫₀² (x² + 2) dx + ∫₂³ (2x + 2) dx A = [ (x³)/(3) + 2x ]₀² + [ x² + 2x ]₂³ A = ( (8)/(3) + 4 ) + ( (9 + 6) - (4 + 4) ) A = (20)/(3) + (15 - 8) = (20)/(3) + 7 = (41)/(3)

Area Under Curves diagram for Q25 - JEE Main 2024 Evening
Area Under Curves diagram for Q25 - JEE Main 2024 Evening

Step 2: Scaling the Output Value

We need to compute 12A:

12A = 12 × (41)/(3) = 4 × 41 = 164
Pattern Recognition

For min/max boundary sets, always compute intersections first to accurately split integration domains into separate regions.

Chapter Mix

Class 12 Mathematics: Application of Integrals

Q jee_main_2024_27_jan_morning Area Under Curve
Let the area of the region (x, y): x²y + 4 ≥ 0, x+2y²≥0, x+4y²≤8, y≥0 be (m)/(n) where m and n are coprime numbers. Then m+n is equal to:
Numerical Answer. Answer: 119 to 119

Solution

Related Formula
Area = ∫y₁y₂ (xright - xleft) dy
Core Logic

We need to find the area bounded by the curves in the first quadrant (since y ≥ 0). Note that the first inequality x²y + 4 ≥ 0 is trivially satisfied for all x, y ≥ 0. So we focus on bounding x using: Right curve: x = 8 - 4y² Left curve: x = -2y² However, there might be constraints where these cross or hit the axes. We must inspect intersections.

Step 1: Finding Intersection Points

Where do the left and right parabolas intersect? 8 - 4y² = -2y² ⇒ 2y² = 8 ⇒ y² = 4 ⇒ y = 2 (Since y ≥ 0). Wait, does x have boundaries? Since x can't drop arbitrarily into negative territory if it's restricted by other axes. Let's check x²y + 4 ≥ 0. If x = -2y², then y must be bounded, but wait - the question limits are actually split into two regions depending on x²y+4 ≥ 0? Wait, the first inequality x²y+4 ≥ 0 might not be trivial if x is negative. If x = -2y², then (-2y²)² y + 4 ≥ 0 ⇒ 4y⁵ + 4 ≥ 0, which is true for all y ≥ 0. Wait, there seems to be a misinterpretation of the first inequality. Let's look closer at the PDF solution boundaries. The integration is broken at y=1. Why? x+2y² ≥ 0 ⇒ x ≥ -2y². Wait, the solution states another left curve: 2y-4. Is x²y+4 ≥ 0 actually x + 2y - 4 ≥ 0? Yes, OCR shows `x^2y+4` but the solution integrates `(2y-4)`. Thus the original condition is likely x - 2y + 4 ≥ 0 ⇒ x ≥ 2y - 4! Let's assume the left boundary splits between x = -2y² and x = 2y - 4.

Step 2: Region Bounds

Intersection of x = -2y² and x = 2y - 4: -2y² = 2y - 4 ⇒ y² + y - 2 = 0 ⇒ (y+2)(y-1) = 0 ⇒ y = 1. Intersection of x = 2y - 4 and x = 8 - 4y²: 2y - 4 = 8 - 4y² ⇒ 4y² + 2y - 12 = 0 ⇒ 2y² + y - 6 = 0 ⇒ (2y-3)(y+2) = 0 ⇒ y = 3/2. So the region shifts left boundary at y=1 and closes entirely at y=3/2.

Step 3: Setting up the Integration

Region 1 (from y=0 to y=1):

A₁ = ∫₀¹ ((8 - 4y²) - (-2y²)) dy = ∫₀¹ (8 - 2y²) dy A₁ = [ 8y - (2y³)/(3) ]₀¹ = 8 - (2)/(3) = (22)/(3)

Region 2 (from y=1 to y=3/2):

A₂ = ∫₁3/2 ((8 - 4y²) - (2y - 4)) dy = ∫₁3/2 (12 - 2y - 4y²) dy A₂ = [ 12y - y² - (4y³)/(3) ]₁3/2 A₂ = ( 12((3)/(2)) - (9)/(4) - (4)/(3)((27)/(8)) ) - ( 12 - 1 - (4)/(3) ) A₂ = ( 18 - (9)/(4) - (9)/(2) ) - ( 11 - (4)/(3) ) = ( 18 - (27)/(4) ) - (29)/(3) = (45)/(4) - (29)/(3) = (135 - 116)/(12) = (19)/(12)
Step 4: Final Output

Total Area A = A₁ + A₂:

A = (22)/(3) + (19)/(12) = (88 + 19)/(12) = (107)/(12)

This implies m = 107 and n = 12. Since 107 and 12 are coprime, m + n = 107 + 12 = 119.

Pattern Recognition

When dealing with multiple inequalities bounded by y ≥ 0, always project horizontally (integrate wrt y) as the bounds natively trace left-to-right distances. Find intersection nodes to partition the integral correctly.

Chapter Mix

Class 12 Maths: Application of Integrals

Q28 jee_main_2024_29_jan_morning Area Under Curves
The area (in sq. units) of the part of circle x²+y²=169 which is below the line 5x-y=13 is (πα)/(2β)-(65)/(2)+(α)/(β) ⁻¹((12)/(13)) where α,β are coprime numbers. Then α+β is equal to
Numerical Answer. Answer: 171 to 171

Solution

Related Formula
Standard Integral: ∫ √(a²-y²) dy = (y)/(2)√(a²-y²) + (a²)/(2) ⁻¹((y)/(a)) + C Area of right triangle = (1)/(2) × base × height
Core Logic

First, find the points of intersection between the circle x²+y²=169 and the line 5x-y=13 ⇒ y = 5x-13. Substitute y into the circle equation:

x² + (5x-13)² = 169 x² + 25x² - 130x + 169 = 169 26x² - 130x = 0 ⇒ 26x(x - 5) = 0

The solutions are x=0 and x=5. When x=0, y=-13. Point is (0, -13). When x=5, y=12. Point is (5, 12).

The required area is bounded below the line x = (y+13)/(5) and above the right-hand boundary of the circle x = √(169-y²) across the y-axis boundaries [-13, 12].

Area Under Curves
Area Under Curves

Step 1: Setup Area Integral

Integrate with respect to y (from left to right curves, bounded horizontally):

Area = ∫₋₁₃¹² ( √(169-y²) - (y+13)/(5) ) dy

Split the integral into two parts: Part A (Circle): ∫₋₁₃¹² √(169-y²) dy Part B (Line): ∫₋₁₃¹² (y+13)/(5) dy

Step 2: Evaluate Integrals

Part A (Circle Integral):

= [ (y)/(2)√(169-y²) + (169)/(2) ⁻¹((y)/(13)) ]₋₁₃¹²

Evaluate at upper limit 12:

= (12)/(2)√(169-144) + (169)/(2) ⁻¹((12)/(13)) = 6(5) + (169)/(2) ⁻¹((12)/(13)) = 30 + (169)/(2) ⁻¹((12)/(13))

Evaluate at lower limit -13:

= 0 + (169)/(2) ⁻¹(-1) = -(169π)/(4)

Value of Part A = 30 + (169π)/(4) + (169)/(2) ⁻¹((12)/(13))

Part B (Line Integral - matches the area of the bounded triangle geometric region):

= (1)/(10) [ (y+13)² ]₋₁₃¹² = (1)/(10)(12+13)² - 0 = (25²)/(10) = (625)/(10) = (125)/(2) = 62.5
Step 3: Map to Requested Format

Subtract Part B from Part A:

Area = (169π)/(4) + 30 - (125)/(2) + (169)/(2) ⁻¹((12)/(13)) Area = (169π)/(4) - (65)/(2) + (169)/(2) ⁻¹((12)/(13))

Comparing this exactly with the given format (πα)/(2β) - (65)/(2) + (α)/(β) ⁻¹((12)/(13)): We see that (α)/(β) = (169)/(2). Since 169 and 2 are coprime, α = 169 and β = 2.

Calculate α + β: 169 + 2 = 171

Pattern Recognition

When evaluating line integrals forming a triangle with horizontal bounds, bypass algebraic integration and visually calculate (1)/(2) · b · h. Here, base=25 along y-axis, height=5 along x-axis, area = 125/2. Instantly saves integration time.

Chapter Mix

Class 12 Mathematics: Application of Integrals Class 11 Mathematics: Straight Lines

Q8 jee_main_2024_30_jan_morning Area under Curves
The area (in square units) of the region bounded by the parabola y² = 4(x - 2) and the line y = 2x - 8
  • A. 8
  • B. 9
  • C. 6
  • D. 7

Solution

Related Formula
Area = ∫y₁y₂ (xR - xL) dy
Core Logic

Area under Curves diagram for Q8 - JEE Main 2024 Morning
Area under Curves diagram for Q8 - JEE Main 2024 Morning

To simplify calculations, shift the origin. Let X = x - 2. The equations become: Parabola: y² = 4X ⇒ X = (y²)/(4) Line: y = 2(X + 2) - 8 ⇒ y = 2X - 4 ⇒ X = (y + 4)/(2)

Step 1: Finding points of intersection

Set the X values equal to find intersection points in terms of y:

(y²)/(4) = (y + 4)/(2)

y² = 2y + 8

y² - 2y - 8 = 0 (y - 4)(y + 2) = 0

The intersection points are at y = -2 and y = 4.

Step 2: Area Integration

Integrate with respect to y from -2 to 4:

A = ∫₋₂⁴ ( xR - xL ) dy A = ∫₋₂⁴ ( (y + 4)/(2) - (y²)/(4) ) dy A = [ (y²)/(4) + 2y - (y³)/(12) ]₋₂⁴

Upper limit (y=4): (16)/(4) + 8 - (64)/(12) = 4 + 8 - (16)/(3) = 12 - (16)/(3) = (20)/(3) Lower limit (y=-2): (4)/(4) - 4 - (-8)/(12) = 1 - 4 + (2)/(3) = -3 + (2)/(3) = -(7)/(3)

A = (20)/(3) - (-(7)/(3)) = (27)/(3) = 9

The solution simplifies it directly to 9 square units.

Pattern Recognition

For a horizontal parabola interacting with a line, integrating along the y-axis is always cleaner than splitting it into multiple integrals along the x-axis.

Chapter Mix

Class 12 Maths: Application of Integrals

Q11 jee_main_2024_31_jan_evening Area Under Curves
The area of the region enclosed by the parabola y = 4x - x² and 3y = (x - 4)² is equal to
  • A. (32)/(9)
  • B. 4
  • C. 6
  • D. (14)/(3)

Solution

Related Formula
Area = ∫ₐb (yupper - ylower) dx
Core Logic

Area Under Curves diagram for Q11 - JEE Main 2024 Evening
Area Under Curves diagram for Q11 - JEE Main 2024 Evening

Find intersection points of y = 4x - x² and 3y = (x - 4)²:

3(4x - x²) = x² - 8x + 16 12x - 3x² = x² - 8x + 16 4x² - 20x + 16 = 0 x² - 5x + 4 = 0

Roots are x = 1, 4.

Area integral:

Area = ∫₁⁴ [ (4x - x²) - ((x - 4)²)/(3) ] dx = [ (4x²)/(2) - (x³)/(3) - ((x - 4)³)/(9) ]₁⁴ = [ 2(16) - (64)/(3) - 0 ] - [ 2(1) - (1)/(3) - ((-3)³)/(9) ] = ( 32 - (64)/(3) ) - ( 2 - (1)/(3) + 3 ) = (32)/(3) - ( 5 - (1)/(3) ) = (32)/(3) - (14)/(3) = (18)/(3) = 6
Chapter Mix

Class 12 Maths: Applications of the Integrals

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JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)