The area of the region enclosed by the parabola (y - 2)^2 = x - 1 , the line x - 2y + 4 = 0 and the positive coordinate axes is

Numerical Answer Type:
Enter a numerical value Answer: 5 to 5 +4 marks

Solution & Explanation

### Related Formula textArea enclosed integrating w.r.t y-axis: int (x_textright - x_textleft) dy ### Core Logic Find intersection points between the parabola x = (y-2)^2 + 1 and the line x = 2y - 4. Set them equal: (y-2)^2 + 1 = 2y - 4 y^2 - 4y + 4 + 1 = 2y - 4 y^2 - 6y + 9 = 0 Rightarrow (y-3)^2 = 0 The line is tangent to the parabola at y = 3. At y = 3, x = 2(3) - 4 = 2. We need the area enclosed by the parabola, the line, and the *positive coordinate axes*. Let's trace the boundary intercepts. The line x = 2y - 4 cuts the y-axis (x=0) at y=2. Parabola vertex is at (1, 2). Parabola cuts y-axis (x=0) at (y-2)^2 = -1 (No real y-intercept). So the curve (y-2)^2 = x-1 only exists for x ge 1. ### Step 1: Setting up the Integral w.r.t y
Area Under Curve diagram for Q29 - JEE Main 2024 Evening
Area Under Curve diagram for Q29 - JEE Main 2024 Evening
Because the area is bound by the positive coordinate axes, we track integration strictly in the first quadrant. The required area is the area between the y-axis, the x-axis, the line, and the curve. Wait, the problem says "area enclosed by the parabola... line... and positive coordinate axes". Let's integrate with respect to y. The boundary curves are x = (y-2)^2 + 1 (which forms the rightmost boundary) and the axes. The area bounded by the curve with y-axis is from y=0 to y=3 minus the triangular region cut by the line below y=2. The line intersects the x-axis (y=0) at x=-4 and y-axis (x=0) at y=2. The positive coordinate axes enforce boundaries at x ge 0, y ge 0. So the exact area is the integral of the parabola's x-value from y=0 to y=3, minus the area of the small triangle outside the region bounded by the line x=2y-4 and the axes in the positive quadrant. The area under the parabola (to the left towards the y-axis) from y=0 to y=3 is int_0^3 x_textparabola dy. The line bounds the region on the left from y=2 to y=3. Between y=0 and y=2, the area goes fully to the y-axis. So, area = int_0^3 x_textparabola dy - textArea of Delta text bounded by line and y-axis. The triangle bounded by x=2y-4, x=0, y=2, y=3 is: base is x=2(3)-4 = 2 at y=3, height is 1 (from y=2 to y=3). Triangle area = frac12 times 2 times 1 = 1. Hence, Enclosed Area = int_0^3 ((y-2)^2 + 1) dy - 1. ### Step 2: Evaluating the Integral textArea = int_0^3 (y^2 - 4y + 5) dy - 1 = left[ fracy^33 - 2y^2 + 5y right]_0^3 - 1 = left( frac273 - 2(9) + 5(3) right) - 0 - 1 = (9 - 18 + 15) - 1 = 6 - 1 = 5 ### Pattern Recognition Instead of evaluating horizontal strips with a broken left-bound, evaluate the total area mapped to the y-axis int_0^3 x dy and simply subtract the basic geometric triangle removed by the straight line. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Integral Calculus

Reference Study Guides

More Integral Calculus Previous-Year Questions

Q57 jee_main_2025_02_april_evening Properties of Definite Integrals
Let (a, b) be the point of intersection of the curve x^2 = 2y and the straight line y - 2x - 6 = 0 in the second quadrant. Then the integral I = int_a^b frac9x^21 + 5^x \, dx is equal to:
  • A. 24
  • B. 27
  • C. 18
  • D. 21

Solution

### Related Formula textKing's Property: int_a^b f(x) dx = int_a^b f(a+b-x) dx ### Core Logic First, we find the coordinates of intersection in the second quadrant to determine the integration limits a and b. ### Step 1: Find points of intersection Substitute y = fracx^22 into the line equation y - 2x - 6 = 0: fracx^22 - 2x - 6 = 0 implies x^2 - 4x - 12 = 0 (x - 6)(x + 2) = 0 implies x = 6 quad textor quad x = -2 Since the point (a, b) lies in the second quadrant, x must be negative: a = -2 b = 2(a) + 6 = 2(-2) + 6 = 2 Thus, the integration limits are a = -2 and b = 2. ### Step 2: Solve the Integral using King's Property The integral is: I = int_-2^2 frac9x^21 + 5^x dx quad text--- (1) Apply King's property, substituting x to -x (since -2 + 2 - x = -x): I = int_-2^2 frac9(-x)^21 + 5^-x dx = int_-2^2 frac9x^2 cdot 5^x1 + 5^x dx quad text--- (2) Adding equations (1) and (2): 2I = int_-2^2 9x^2 left( frac1 + 5^x1 + 5^x right) dx = int_-2^2 9x^2 dx Since 9x^2 is an even function: 2I = 2 int_0^2 9x^2 dx implies I = left[ 3x^3 right]_0^2 = 3(8) - 0 = 24 ### Pattern Recognition Whenever you see an exponential denominator like 1 + c^x inside a symmetric interval definite integral [-a, a], applying King's property will almost always cancel the exponential factor cleanly when the remaining numerator is even. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Integral Calculus
Q63 jee_main_2025_02_april_evening Integration by Rationalisation
4int_0^1left(frac1sqrt3 + x^2 + sqrt1 + x^2right)mathrmdx - 3log_eleft(sqrt3right) is equal to:
  • A. 2 + sqrt2 + log_mathrmeleft(1 + sqrt2right)
  • B. 2 - sqrt2 - log_mathrmeleft(1 + sqrt2right)
  • C. 2 + sqrt2 - log_mathrmeleft(1 + sqrt2right)
  • D. 2 - sqrt2 + log_mathrmeleft(1 + sqrt2right)

Solution

### Related Formula int sqrta^2 + x^2 dx = fracx2 sqrta^2 + x^2 + fraca^22 lnleft| x + sqrta^2 + x^2 right| ### Core Logic We first rationalise the denominator to split the integral into two standard integration terms. ### Step 1: Rationalise the integrand Multiply the numerator and denominator by sqrt3+x^2 - sqrt1+x^2: frac1sqrt3 + x^2 + sqrt1 + x^2 = fracsqrt3 + x^2 - sqrt1 + x^2(3+x^2) - (1+x^2) = fracsqrt3 + x^2 - sqrt1 + x^22 Thus, the integral expression simplifies to: I = 4 int_0^1 left( fracsqrt3 + x^2 - sqrt1 + x^22 right) dx - 3log_eleft(sqrt3right) I = 2 int_0^1 sqrt3 + x^2 dx - 2 int_0^1 sqrt1 + x^2 dx - frac32 log_e 3 ### Step 2: Evaluate the integrals For the first integral: 2 int_0^1 sqrt3 + x^2 dx = 2 left[ fracx2 sqrt3 + x^2 + frac32 lnleft| x + sqrt3 + x^2 right| right]_0^1 = left[ x sqrt3 + x^2 + 3 lnleft| x + sqrt3 + x^2 right| right]_0^1 = left( sqrt4 + 3 ln(1 + sqrt4) right) - left( 0 + 3 lnsqrt3 right) = 2 + 3 ln 3 - frac32 ln 3 = 2 + frac32 ln 3 For the second integral: -2 int_0^1 sqrt1 + x^2 dx = -2 left[ fracx2 sqrt1 + x^2 + frac12 lnleft| x + sqrt1 + x^2 right| right]_0^1 = - left[ x sqrt1 + x^2 + lnleft| x + sqrt1 + x^2 right| right]_0^1 = - left( sqrt2 + ln(1 + sqrt2) right) ### Step 3: Sum the terms Now compile all terms: I = left( 2 + frac32 ln 3 right) - sqrt2 - ln(1 + sqrt2) - frac32 ln 3 I = 2 - sqrt2 - ln(1 + sqrt2) ### Pattern Recognition Integration of roots of quadratics: Always look for algebraic rationalisation when dealing with sum of root denominators. It directly reduces complex fractions into standard integrable functions. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Integral Calculus
Q71 jee_main_2025_02_april_morning Definite Integration with GIF
Let [cdot] denote the greatest integer function. If int_0^e^3left[frac1e^x - 1right]mathrmdx = alpha -log_e2, then alpha^3 is equal to ________.
Numerical Answer. Answer: 8 to 8

Solution

### Related Formula Greatest Integer Function boundaries: [f(x)] = k quad textfor quad k le f(x) < k+1, \ k in mathbbZ ### Core Logic Analyze the value variations of f(x) = e^1-x across the integration limits [0, e^3] to break down the integral into distinct piecewise continuous intervals. ### Step 1: Determine Step Function Transition Points Let y = e^1-x. * At x = 0 implies y = e^1 approx 2.718 * As x increases, e^1-x decreases monotonically. * Find x where y = 2 implies e^1-x = 2 implies 1-x = ln 2 implies x = 1 - ln 2. * Find x where y = 1 implies e^1-x = 1 implies 1-x = 0 implies x = 1. * At the final boundary x = e^3 implies y = e^1-e^3, which is a very small positive decimal strictly inside (0,1). ### Step 2: Split the Definite Integral Rewrite the integral based on the isolated interval blocks: I = int_0^1-ln 2 2 \, mathrmdx + int_1-ln 2^1 1 \, mathrmdx + int_1^e^3 0 \, mathrmdx ### Step 3: Perform Integrations I = 2[x]_0^1-ln 2 + 1[x]_1-ln 2^1 + 0 I = 2(1 - ln 2 - 0) + 1(1 - (1 - ln 2)) = 2 - 2ln 2 + ln 2 = 2 - ln 2 ### Step 4: Solve for Alpha Cubed Compare the integrated value to alpha - ln 2: alpha - ln 2 = 2 - ln 2 implies alpha = 2 alpha^3 = 2^3 = 8 ### Pattern Recognition Always map the function values at the extreme boundary points first. Tracking the downward path from 2.71 rightarrow 2 rightarrow 1 rightarrow 0 reveals exactly where the integer thresholds are crossed. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Integrals
Q59 jee_main_2025_03_april_evening Definite Integrals
The integral int_0^pi frac8x \, dx4cos^2 x + sin^2 x is equal to
  • A. 2pi^2
  • B. 4pi^2
  • C. pi^2
  • D. frac3pi^22

Solution

### Related Formula Using the properties of definite integrals: int_a^b f(x) \, dx = int_a^b f(a+b-x) \, dx Also, if f(2a-x) = f(x), then: int_0^2a f(x) \, dx = 2 int_0^a f(x) \, dx ### Core Logic Let: I = int_0^pi frac8x \, dx4cos^2 x + sin^2 x quad text--- (1) Applying x to pi-x: I = int_0^pi frac8(pi - x) \, dx4cos^2 x + sin^2 x quad text--- (2) ### Step 1: Eliminating the x term in numerator Adding (1) and (2): 2I = 8pi int_0^pi fracdx4cos^2 x + sin^2 x I = 4pi int_0^pi fracdx4cos^2 x + sin^2 x Since the integrand is symmetric about x = pi/2: I = 8pi int_0^pi/2 fracdx4cos^2 x + sin^2 x ### Step 2: Integration using sec^2 x substitution Divide numerator and denominator by cos^2 x: I = 8pi int_0^pi/2 fracsec^2 x \, dx4 + tan^2 x Let t = tan x implies dt = sec^2 x \, dx At x = 0, t = 0; at x = pi/2, t to infty. I = 8pi int_0^infty fracdtt^2 + 2^2 I = 8pi left[ frac12 tan^-1left(fract2right) right]_0^infty = 4pi left( fracpi2 - 0 right) = 2pi^2 ### Pattern Recognition The presence of a linear x factor in the numerator of a definite integral with symmetric trigonometric bounds is almost always eliminated using the a+b-x property. This reduces the integral to a standard substitution problem. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Integrals
Q53 jee_main_2025_29_jan_evening Area Enclosed by Two Curves
Let the area enclosed between the curves |y| = 1 - x^2 and x^2 + y^2 = 1 be alpha. If 9alpha = beta pi + gamma, beta, gamma are integers, then the value of |beta - gamma| equals
  • A. 27
  • B. 18
  • C. 15
  • D. 33

Solution

### Related Formula Area enclosed between two symmetric functions across four quadrants: alpha = 4 times left( textArea of circle in 1^textst text quadrant - int_0^1 y_textparabola \, dx right) ### Core Logic The curves are symmetric across the axes. The region is enclosed between the unit circle x^2 + y^2 = 1 and the parabolas y = pm(1 - x^2).
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 alpha 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 fracpi4. Area under the parabola: int_0^1 (1 - x^2) \, dx = left[ x - fracx^33 right]_0^1 = 1 - frac13 = frac23 ### Step 2: Evaluate the Total Area alpha = 4 left[ fracpi4 - frac23 right] = pi - frac83 Multiplying both sides by 9: 9alpha = 9pi - 24 Comparing with 9alpha = betapi + gamma, we get: beta = 9, quad gamma = -24 Hence, |beta - gamma| = |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. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Integral Calculus

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