The value of ∫₋₁¹ (1 + √(|x| - x))e^x + (√(|x| - x))e-xe^x + e-x dx is equal to

Solution & Explanation

Related Formula

King's property of definite integrals:

∫ₐb f(x)dx = ∫ₐb f(a+b-x)dx
Core Logic

Let the given integral be I. Apply King's property by substituting x → -x:

I = ∫₋₁¹ (1 + √(|x| + x))e-x + (√(|x| + x))exe-x + ex dx

Add both integral expressions 2I = I + I:

2I = ∫₋₁¹ (e^x + e-x) + (√(|x| - x) + √(|x| + x))(e^x + e-x)e^x + e-x dx 2I = ∫₋₁¹ (1 + √(|x| - x) + √(|x| + x)) dx
Step 1: Apply Symmetry Properties

The integrand is completely even. Hence, convert intervals:

2I = 2∫₀¹ (1 + √(|x| - x) + √(|x| + x)) dx

For x in [0,1], |x| = x √(|x| - x) = 0 and √(|x| + x) = √(2x):

I = ∫₀¹ (1 + √(2x)) dx
Step 2: Final Integration Execution
I = [ x + √(2) · x3/23/2 ]₀¹ = [ x + 2√(2)3x3/2 ]₀¹ I = 1 + 2√(2)3
Pattern Recognition

When functions involve combinations of exponential components (e^x, e-x) over symmetric boundaries, adding the variable reflection eliminates exponential fractions instantly.

Chapter Mix

Class 12 Mathematics: Definite Integration

Reference Study Guides

More Definite Integration Previous-Year Questions — Page 6

Q53 jee_main_2025_29_jan_evening Area Enclosed by Two Curves
Let the area enclosed between the curves |y| = 1 - x² and x² + y² = 1 be α. If 9α = β π + γ, β, γ are integers, then the value of |β - γ| equals
  • A. 27
  • B. 18
  • C. 15
  • D. 33

Solution

Related Formula

Area enclosed between two symmetric functions across four quadrants:

α = 4 × ( Area of circle in 1st quadrant - ∫₀¹ yparabola dx )
Core Logic

The curves are symmetric across the axes. The region is enclosed between the unit circle x² + y² = 1 and the parabolas y = ±(1 - x²).

Area Enclosed by Two Curves diagram for Q53 - JEE Main 2025 Evening
Area Enclosed by Two Curves diagram for Q53 - JEE Main 2025 Evening

By symmetry, the area α in the first quadrant is the area under the circle minus the area under the parabola from x=0 to x=1.

Step 1: Calculate the Area Components

Area of a circle quadrant with r=1 is (π)/(4).

Area under the parabola:

∫₀¹ (1 - x²) dx = [ x - (x³)/(3) ]₀¹ = 1 - (1)/(3) = (2)/(3)
Step 2: Evaluate the Total Area
α = 4 [ (π)/(4) - (2)/(3) ] = π - (8)/(3)

Multiplying both sides by 9:

9α = 9π - 24

Comparing with 9α = βπ + γ, we get:

β = 9, γ = -24

Hence,

|β - γ| = |9 - (-24)| = 33
Pattern Recognition

Symmetry helps divide the integration work by 4. Recognizing standard shapes (like a circle sector) allows you to bypass complex integration entirely for half of the problem.

Chapter Mix

Class 12 Mathematics: Integral Calculus

Q71 jee_main_2025_29_jan_evening Integration of Modulus and Greatest Integer Functions
If 24∫₀(pi)/(4)( |4x - (pi)/(12)| + [2 x])dx = 2π +α, where [· ] denotes the greatest integer function, then α is equal to
Numerical Answer. Answer: 12 to 12

Solution

Related Formula

Additivity property of definite integrals over split interval boundary points:

∫ₐc g(x) dx = ∫ₐb g(x) dx + ∫bc g(x) dx
Core Logic

Separate the integration tracking flow into two component operations:

I₁ = ∫₀(pi)/(4) |4x - (pi)/(12)| dx I₂ = ∫₀(pi)/(4) [2 x] dx
Step 1: Solve Modulus Integral Term

The argument changes sign inside absolute value bounds when 4x - (pi)/(12) = 0 x = (pi)/(48):

I₁ = ∫₀(pi)/(48) - (4x - (pi)/(12)) dx + ∫(pi)/(48)(pi)/(4) (4x - (pi)/(12)) dx = (1)/(4) [ (4x - (pi)/(12)) ]₀(pi)/(48) - (1)/(4) [ (4x - (pi)/(12)) ](pi)/(48)(pi)/(4)

Evaluating across numerical boundaries gives:

24 · I₁ = 24((1)/(2)) = 12
Step 2: Solve Greatest Integer Component and Combine

Analyze step limits inside greatest integer block [2 x]: For x in [0, (pi)/(6)), 0 ≤ 2 x < 1 [2 x] = 0. For x in [(pi)/(6), (pi)/(4)], 1 ≤ 2 x < √(2) [2 x] = 1.

I₂ = ∫₀(pi)/(6) 0 dx + ∫(pi)/(6)(pi)/(4) 1 dx = (pi)/(4) - (pi)/(6) = (pi)/(12)

Combine both sections aggregated by multiplier 24:

Total = 12 + 24((pi)/(12)) = 2π + 12

Comparing directly with expression statement parameters 2π + α isolates response value: α = 12

Pattern Recognition

Modulus arguments and step functions require isolating inflection transition numbers directly to break integrations up neatly.

Chapter Mix

Class 12 Mathematics: Definite Integration

Q jee_main_2025_28_jan_morning Properties of Definite Integrals (King's Property)
If ∫-(π)/(2)(π)/(2)(96x² ²x)/((1 + e^x)) dx = π (α π² +β),α ,β in Z, then (α + β)² equals:
  • A. 144
  • B. 196
  • C. 100
  • D. 64

Solution

Related Formula

King's property for definite integration:

∫ₐ^b f(x) dx = ∫ₐ^b f(a+b-x) dx
Core Logic

Apply the identity x → -x to the integral:

I = ∫-(π)/(2)(π)/(2) (96x² ² x)/(1 + e^x) dx = ∫-(π)/(2)(π)/(2) 96x² ² x1 + e-x dx
Step 1: Adding both integral variations

Adding the equations eliminates the exponential denominator term (1+e^x):

2I = ∫-(π)/(2)(π)/(2) 96x² ² x · [(1)/(1+e^x) + (e^x)/(1+e^x)] dx I = 48 ∫₀(π)/(2) x² (1 + 2x) dx
Step 2: Evaluating the integrated components

Integrating by parts gives:

I = π (2π² - 12)

Matching coefficients with the template: α = 2 and \beta = -12.

(α + β)² = (2 - 12)² = (-10)² = 100
Pattern Recognition

Exponential denominators like 1+e^x in symmetric integral intervals are prime candidates for simplification using King's property.

Chapter Mix

Class 12 Maths: Definite Integrals

Q65 jee_main_2025_03_april_morning Methods of Integration by Substitution
Let f(x) = ∫ x³√(3 - x²) dx[cite: 635, 637]. If 5f(√(2)) = -4 [cite: 638], then f(1) is equal to[cite: 642]:
  • A. - 2√(2)5
  • B. - 8√(2)5
  • C. - 4√(2)5
  • D. - 6√(2)5

Solution

Related Formula

Method of algebraic parameter substitution: Set 3-x² = t² -2xdx = 2tdt xdx = -tdt

Core Logic

Perform the specified variable parameter replacement steps [cite: 1361, 1362]: 3 - x² = t² x dx = -t dt [cite: 1361, 1362] Rewrite the internal integral block components [cite: 1363]: f(x) = ∫ x² · √(3-x²) · (x dx) = ∫ (3-t²) · t · (-t dt) [cite: 1363] = ∫ (t⁴ - 3t²) dt = (t⁵)/(5) - t³ + C [cite: 1363, 1366]

Return to original reference variable x [cite: 1366]: f(x) = (3-x²)5/25 - (3-x²)3/2 + C [cite: 1366]

Step 1: Constant integration resolving

Evaluate function boundary conditions at x = √(2) [cite: 1366]: f(√(2)) = (3-2)5/25 - (3-2)3/2 + C = (1)/(5) - 1 + C = -(4)/(5) + C [cite: 1366] Given 5f(√(2)) = -4 f(√(2)) = -(4)/(5) [cite: 638, 1366]. -(4)/(5) + C = -(4)/(5) C = 0 [cite: 1366]

Step 2: Numeric tracking value

Evaluate final targeted definition state value at x=1 [cite: 1367]: f(1) = (3-1)5/25 - (3-1)3/2 = 25/25 - 23/2 [cite: 1367] = 23/2((2)/(5) - 1) = 2√(2)(-(3)/(5)) = - 6√(2)5 [cite: 1367, 1368]

Pattern Recognition

Splitting powers of x to create a direct match with internal derivative differential flags speeds up the integration transformation sequence.

Chapter Mix

Class 12 Mathematics: Integrals

Q67 jee_main_2025_03_april_morning Definite Integral of Greatest Integer Function
Let the domain of the function f(x) = ₂ ₄ ₆(3 + 4x - x²) be (a, b)[cite: 663]. If ∫₀b-a[x²]dx = p - √(q) - √(r) [cite: 664], where p, q, r in N [cite: 664] and (p, q, r) = 1 [cite: 668], and [·] represents the greatest integer function [cite: 668], then p + q + r is equal to[cite: 668]:
  • A. 10
  • B. 8
  • C. 11
  • D. 9

Solution

Related Formula

Domain of log chain iterations: For ₂ ₄(M) > 0, we require ₄(M) > 1 M > 4.

Core Logic

Trace internal arguments outward sequentially [cite: 1393, 1394]: ₄ ₆(3 + 4x - x²) > 0 ₆(3 + 4x - x²) > 1 [cite: 1393, 1394] 3 + 4x - x² > 6¹ x² - 4x + 3 < 0 [cite: 1395, 1396] (x-1)(x-3) < 0 x in (1, 3) [cite: 1397, 1398]

Thus, determine limits [cite: 1399]: a = 1, b = 3 b - a = 2 [cite: 1399]

Step 1: Setting up the greatest integer function integration

We need to evaluate ∫₀² [x²] dx[cite: 1400]. Identify step boundary switch locations inside range [0, 2] [cite: 1400]:

  • For x in [0, 1): [x²] = 0
  • For x in [1, √(2)): [x²] = 1
  • For x in [√(2), √(3)): [x²] = 2
  • For x in [√(3), 2): [x²] = 3
  • Set up separate boundary component integrations [cite: 1400]: ∫₀² [x²] dx = ∫₀¹ 0 dx + ∫₁√(2) 1 dx + ∫√(2)√(3) 2 dx + ∫√(3)² 3 dx [cite: 1400] = 0 + (√(2) - 1) + 2(√(3) - √(2)) + 3(2 - √(3)) [cite: 1400] = √(2) - 1 + 2√(3) - 2√(2) + 6 - 3√(3) = 5 - √(2) - √(3) [cite: 1400]

Step 2: Matching coefficients

Compare values with requested answer template shape [cite: 1400]: 5 - √(2) - √(3) = p - √(q) - √(r) [cite: 1400] p = 5, q = 2, r = 3 [cite: 1400]

Final Sum = p + q + r = 5 + 2 + 3 = 10 [cite: 1400]

Pattern Recognition

Integrals over greatest integer configurations change value exactly where the inner expression tracks through integer milestones. Mapping boundaries accurately resolves calculations smoothly.

Chapter Mix

Class 12 Mathematics: Integrals

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