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Integral Calculus appeared 62 times across 3 years — 7.2% of Mathematics. This question is from Indefinite Integration.

Year 2026 2025 2024 Total
Questions 18 26 18 62

For xin(-(π)/(2),(π)/(2)), if y(x)=∫ cosec x+ xcosec x x+ x ² xdx and xarrow((π)/(2))^-y(x)=0 then y((π)/(4)) is equal to

Solution & Explanation

Related Formula
∫ (1)/(u² + a²) du = (1)/(a) ⁻¹((u)/(a)) + C
Core Logic

Simplify the given integrand by converting all trigonometric ratios into x and x:

I = cosec x + xcosec x x + x ² x

Numerator: (1)/( x) + x = (1 + ² x)/( x)

Denominator: (1)/( x x) + ( x)/( x) · ² x = (1 + ⁴ x)/( x x)

Divide Numerator by Denominator:

I = ((1 + ² x)/( x))/((1 + ⁴ x)/( x x)) = ((1 + ² x) x)/(1 + ⁴ x)
Step 1: Apply Substitution

Now rewrite the integral:

y(x) = ∫ ((1 + ² x) x)/(1 + ⁴ x) dx

Let x = t, then x dx = dt. The integral becomes:

y(x) = ∫ (1 + t²)/(1 + t⁴) dt

Divide numerator and denominator by t²:

y(x) = ∫ (1 + (1)/(t²))/(t² + (1)/(t²)) dt

We know that t² + (1)/(t²) = (t - (1)/(t))² + 2. Let u = t - (1)/(t), then du = (1 + (1)/(t²)) dt.

y(x) = ∫ duu² + (√(2))² = 1√(2) ⁻¹( u√(2)) + C y(x) = 1√(2) ⁻¹( t - 1/t√(2)) + C = 1√(2) ⁻¹( x - cosec x√(2)) + C
Step 2: Solve for Constant C

We are given that xarrow(π/2)^- y(x) = 0. As x → (π)/(2), x → 1 and cosec x → 1. Thus, x - cosec x → 0.

0 = 1√(2) ⁻¹( 1 - 1√(2)) + C 0 = 1√(2) ⁻¹(0) + C ⇒ C = 0
Step 3: Find y(pi/4)

Substitute x = (π)/(4) into the exact solution y(x) = 1√(2) ⁻¹( x - cosec x√(2)):

At x = (π)/(4), ((π)/(4)) = 1√(2) and cosec((π)/(4)) = √(2).

y((π)/(4)) = 1√(2) ⁻¹( 1√(2) - √(2)√(2)) = 1√(2) ⁻¹( 1 - 2√(2)√(2)) = 1√(2) ⁻¹( -1/√(2)√(2)) = 1√(2) ⁻¹(-(1)/(2))
Pattern Recognition

A high-degree polynomial of x or x in the denominator matched with their derivative elements on top is the hallmark of the t+1/t or t-1/t structural substitution form. Dividing out the middle power (t²) aligns the differential instantly.

Chapter Mix

Class 12 Mathematics: Integral Calculus

Reference Study Guides

More Integral Calculus Previous-Year Questions — Page 9

Q jee_main_2025_28_jan_evening Integration by Parts
Let f: Rarrow R be a twice differentiable function such that f(2)=1. If F(x)=xf(x) for all xin R, ∫₀²xF(x)dx=6 and ∫₀²x²F(x)dx=40, then F(2)+∫₀²F(x)dx is equal to:
  • A. 11
  • B. 15
  • C. 6
  • D. 13

Solution

Related Formula

Integration by Parts formula:

∫ u · v dx = u ∫ v dx - ∫ ( u' ∫ v dx ) dx
Core Logic

Given F(x) = xf(x) and f(2) = 1 F(2) = 2f(2) = 2.

Let's apply Integration by Parts to the first given integral:

∫₀² x F'(x) dx = 6 [ xF(x) ]₀² - ∫₀² F(x) dx = 6 2F(2) - 0 - ∫₀² F(x) dx = 6 2(2) - ∫₀² F(x) dx = 6 ∫₀² F(x) dx = 4 - 6 = -2
Step 1: Simplify Second Integral via Integration by Parts

Now look at the second integral:

∫₀² x² F''(x) dx = 40

Applying Integration by parts (taking u = x² and v = F''(x)):

[ x² F'(x) ]₀² - ∫₀² 2x F'(x) dx = 40 4 F'(2) - 0 - 2 ∫₀² x F'(x) dx = 40

We already know ∫₀² x F'(x) dx = 6:

4 F'(2) - 2(6) = 40 4 F'(2) - 12 = 40 4 F'(2) = 52 F'(2) = 13
Step 2: Sum the Values

We need to find F'(2) + ∫₀² F(x) dx: 13 + (-2) = 11

Pattern Recognition

Notice how the definition of f(x) is mostly a distraction to find F(2)=2. The problem is fundamentally testing consecutive applications of integration by parts to reduction structures.

Chapter Mix

Class 12 Mathematics: Definite Integration

Q57 jee_main_2025_28_jan_evening Leibnitz Rule and Definite Integral
Let f be a real valued continuous function defined on the positive real axis such that g(x)=∫₀xtf(t)dt. If g(x³)=x⁶+x⁷ then value of Σr=1¹⁵f(r³) is:
  • A. 320
  • B. 340
  • C. 270
  • D. 310

Solution

Related Formula

Newton-Leibnitz Theorem for differentiation under integral sign:

(d)/(dx) ( ∫₀x tf(t) dt ) = xf(x)
Core Logic

Given:

g(x) = ∫₀x tf(t) dt

Differentiating both sides with respect to x:

g'(x) = xf(x) f(x) = (g'(x))/(x)

We are given g(x³) = x⁶ + x⁷. Let y = x³ x = y1/3. Substituting this into the expression for g:

g(y) = (y1/3)⁶ + (y1/3)⁷ = y² + y7/3

Thus, replacing y back with x:

g(x) = x² + x7/3
Step 1: Differentiate g(x) to find f(x)
g'(x) = 2x + (7)/(3)x4/3

Now find f(x):

f(x) = (g'(x))/(x) = 2x + (7)/(3)x4/3x = 2 + (7)/(3)x1/3
Step 2: Evaluate the Summation

We need to find Σr=1¹⁵ f(r³):

f(r³) = 2 + (7)/(3)(r³)1/3 = 2 + (7)/(3)r

Now, compute the summation from r=1 to 15:

Σr=1¹⁵ f(r³) = Σr=1¹⁵ ( 2 + (7)/(3)r ) = Σr=1¹⁵ 2 + (7)/(3)Σr=1¹⁵ r (2 × 15) + (7)/(3) × (15 × 16)/(2) 30 + (7)/(3) × 120 = 30 + 7 × 40 = 30 + 280 = 310
Pattern Recognition

Converting g(x³) directly into a function of variable y=x³ prevents multi-layer chain rule complications when applying differentiation immediately.

Chapter Mix

Class 11 Mathematics: Sequences and Series Class 12 Mathematics: Definite Integration

Q66 jee_main_2025_29_jan_morning Integration by Substitution
The integral 80∫₀(π)/(4)(( θ + θ)/(9 + 16 2θ))dθ is equal to:
  • A. 3 ₑ4
  • B. 6 ₑ₄
  • C. 4 ₑ₃
  • D. 2 ₑ3

Solution

Related Formula
∫ (dt)/(a² - b² t²) = (1)/(2a) ln | (a+bt)/(a-bt) | 2θ = 1 - ( θ - θ)²
Core Logic

Let θ - θ = t. Then ( θ + θ)dθ = dt. Transform limits: When θ = 0 t = 0 - 1 = -1 When θ = (π)/(4) t = 1√(2) - 1√(2) = 0

Step 1: Perform the algebraic substitution

Express the denominator base:

9 + 16 2θ = 9 + 16[1 - t²] = 25 - 16t²

The integral transforms to:

I = 80 ∫₋₁⁰ (dt)/(25 - 16t²) = (80)/(16) ∫₋₁⁰ (dt)/(((5)/(4))² - t²)
Step 2: Execute Integral Calculation
I = 5 [ (1)/(2((5)/(4))) ln | ((5)/(4) + t)/((5)/(4) - t) | ]₋₁⁰ I = 2 [ ln(1) - ln( (1/4)/(9/4) ) ] = 2 [ 0 - ln((1)/(9)) ] = 2ln(9) = 4ln(3)
Pattern Recognition

Whenever ( θ + θ) sits inside the numerator, instantly choose t = θ - θ as your core linear substitution engine to clean denominators.

Chapter Mix

Class 12 Mathematics: Definite Integrals

Q71 jee_main_2025_29_jan_morning Functional Equations with Integrals
Let f: (0, ∞) → R be a twice differentiable function. If for some a ≠ 0 , ∫₀¹ f(λ x) dλ = a f(x) , f(1) = 1 and f(16) = (1)/(8) , then 16 - f'((1)/(16)) is equal to
Numerical Answer. Answer: 112

Solution

Related Formula
Leibniz Integral Rule for differentiation: (d)/(dx)∫₀x f(t) dt = f(x)
Core Logic

Perform variable substitution inside the integral: let λ x = t dλ = (1)/(x) dt. When λ = 0 t = 0; when λ = 1 t = x. The equation transforms to:

(1)/(x) ∫₀x f(t) dt = a f(x) ∫₀x f(t) dt = a x f(x)
Step 1: Differentiate with respect to x

Using Leibniz rule and product rule:

f(x) = a [x f'(x) + f(x)] (1 - a)f(x) = a x f'(x) (f'(x))/(f(x)) = (1-a)/(a) (1)/(x)

Integrating both sides yields:

ln f(x) = ((1-a)/(a))ln x + c f(x) = C x(1-a)/(a)
Step 2: Calculate Constants using boundaries

Given f(1) = 1 C = 1. Given f(16) = (1)/(8) (1)/(8) = (16)(1-a)/(a) 2⁻³ = (2⁴)(1-a)/(a)

-3 = (4(1-a))/(a) -3a = 4 - 4a a = 4

Therefore, power exponent = (1-4)/(4) = -(3)/(4) f(x) = x-(3)/(4).

Step 3: Evaluate target derivative value

Find the derivative:

f'(x) = -(3)/(4) x-(7)/(4)

Substitute x = (1)/(16):

f'((1)/(16)) = -(3)/(4) (2⁻⁴)-(7)/(4) = -(3)/(4) (2⁷) = -(3)/(4) × 128 = -96

Final requested computation calculation:

16 - f'((1)/(16)) = 16 - (-96) = 112
Pattern Recognition

Scaling inputs inside functional definite integrals tracks closely to homogenous Euler equation properties. Converting integrations quickly to local power functions reduces processing parameters.

Chapter Mix

Class 12 Mathematics: Definite Integrals Class 12 Mathematics: Differential Equations

Q2 jee_main_2024_01_february_morning Properties of Definite Integrals
The value of the integral ∫₀(π)/(4) x dx ⁴(2x)+ ⁴(2x) equals:
  • A. √(2)π²8
  • B. √(2)π²16
  • C. √(2)π²32
  • D. √(2)π²64

Solution

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:

I = ∫₀(π)/(4) x dx ⁴(2x)+ ⁴(2x)

Substitute 2x = t 2dx = dt dx = (1)/(2)dt. When x = 0 t = 0, and when x = (π)/(4) t = (π)/(2).

I = (1)/(4) ∫₀(π)/(2) t dt ⁴t + ⁴t (1)
Step 1: Apply King's Property

Applying the property ∫₀a f(t) dt = ∫₀a f(a-t) dt:

I = (1)/(4) ∫₀(π)/(2) ((π)/(2) - t) dt ⁴((π)/(2)-t) + ⁴((π)/(2)-t) I = (1)/(4) ∫₀(π)/(2) ((π)/(2) - t) dt ⁴t + ⁴t (2)

Adding equations (1) and (2):

2I = (1)/(4) ∫₀(π)/(2) (π)/(2) dt ⁴t + ⁴t 2I = (π)/(8) ∫₀(π)/(2) dt ⁴t + ⁴t 2I = (π)/(8) ∫₀(π)/(2) ⁴t dt ⁴t + 1 2I = (π)/(8) ∫₀(π)/(2) (1 + ²t) ²t dt ⁴t + 1
Step 2: Substitution and Algebraic Limits

Let t = y ²t dt = dy. When t = 0 y = 0, and when t = (π)/(2) y = ∞.

2I = (π)/(8) ∫₀∞ (1 + y²) dy1 + y⁴ I = (π)/(16) ∫₀∞ 1 + 1y²y² + 1y² dy

Now put y - (1)/(y) = p (1 + 1y²) dy = dp. When y → 0^+ p → -∞, and when y → ∞ p → ∞. Also, y² + 1y² = p² + 2 = p² + (√(2))².

I = (π)/(16) ∫-∞∞ dpp² + (√(2))² I = π16√(2) [ ⁻¹( p√(2)) ]-∞∞ I = π16√(2) ( (π)/(2) - (-(π)/(2)) ) = π²16√(2) = √(2)π²32$$
Pattern Recognition

Sees: Integrand containing

Pattern Recognition

Sees: Integrand containing $xin the numerator and symmetric trigonometric functions in the denominator. Shortcut: The elimination ofxusing King's property is standard. For integrals containing\frac{1+y^2}{1+y^4}, dividing byy^2transforms the denominator into a perfect square form\left(y-\frac{1}{y}\right)^2+2$, making substitution trivial.

Chapter Mix

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