The area of the region bounded by the curves x(1+y²)=1 and y²=2x is :

Solution & Explanation

Related Formula

Area integrating with respect to y:

A = ∫y₁y₂ (xright - xleft) dy

Standard integral:

∫ (1)/(1+y²) dy = ⁻¹(y)
Core Logic

The boundary curves are:

  • x = (1)/(1+y²)
  • x = (y²)/(2)
  • Find intersection points by setting x equal:

(1)/(1+y²) = (y²)/(2) 2 = y²(1+y²) y⁴ + y² - 2 = 0 (y² + 2)(y² - 1) = 0

Since y is real, y² = 1 y = ± 1. When y = ± 1, x = (1)/(2). Intersection points are ((1)/(2), 1) and ((1)/(2), -1).

Step 1: Set up and Compute Area Integral

Between y = -1 and y = 1, (1)/(1+y²) ≥ (y²)/(2).

Area = ∫₋₁¹ ( (1)/(1+y²) - (y²)/(2) ) dy

Since the integrand is an even function of y:

Area = 2 ∫₀¹ ( (1)/(1+y²) - (y²)/(2) ) dy Area = 2 [ ⁻¹(y) - (y³)/(6) ]₀¹ Area = 2 [ ⁻¹(1) - (1)/(6) - (0) ] = 2 ( (π)/(4) - (1)/(6) ) = (π)/(2) - (1)/(3)
Pattern Recognition

Whenever curves are functions of y², integrating along the y-axis avoids dealing with messy radical functions (square roots) and naturally accounts for symmetry across the x-axis.

Chapter Mix

Class 12 Mathematics: Application of Integrals

More Area Under Curves Previous-Year Questions — Page 6

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

Q5 jee_main_2024_31_jan_morning Area bounded by Parabolas and Inequalities
The area of the region (x,y): y² ≤ 4x, x < 4, (xy(x - 1)(x - 2))/((x - 3)(x - 4)) > 0, x ≠ 3 is
  • A. (16)/(3)
  • B. (64)/(3)
  • C. (8)/(3)
  • D. (32)/(3)

Solution

Core Logic

Given y² ≤ 4x and x < 4. Analyze the inequality (xy(x-1)(x-2))/((x-3)(x-4)) > 0 considering y > 0 and y < 0 separately.

Area bounded by Parabolas and Inequalities diagram for Q5 - JEE Main 2024 Morning
Area bounded by Parabolas and Inequalities diagram for Q5 - JEE Main 2024 Morning

Step 1: Case I (y > 0)

If y > 0, the inequality reduces to (x(x-1)(x-2))/((x-3)(x-4)) > 0. Using wavy curve method and given x in (0, 4): x in (0, 1) (2, 3).

Step 2: Case II (y < 0)

If y < 0, the inequality reduces to (x(x-1)(x-2))/((x-3)(x-4)) < 0. Using wavy curve method and given x in (0, 4): x in (1, 2) (3, 4).

Step 3: Area Computation

Because the regions map perfectly without overlap in opposite quadrants relative to the x-axis, they form complete parabolic strips when combined: Area = 2 ∫₀⁴ √(x) dx = 2 · (2)/(3)[x3/2]₀⁴ = (4)/(3) · 8 = (32)/(3).

Chapter Mix

Class 12 Maths: Area Under Curves Class 11 Maths: Linear Inequalities

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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%)