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JEE Main 20264 AprilEvening Shift
Exam
JEE Main
Year
2026
Date
4 April
Shift
Evening Shift
Subject
Mathematics
Chapter
Differential Equations

JEE Main 2026 · 4 April · Evening Shift · Mathematics · Differential Equations

Let y=y(x) be the solution of the differential equation:...

Let y=y(x)y=y(x) be the solution of the differential equation: dydx+(6x2+(3x2+2x3+4)e−2x(x3+2)(2+e−2x))y=2+e−2x\dfrac{dy}{dx}+\left(\dfrac{6x^2+(3x^2+2x^3+4)e^{-2x}}{(x^3+2)(2+e^{-2x})}\right)y=2+e^{-2x}, x∈(−1,2)x \in (-1,2), satisfying y(0)=32y(0)=\dfrac{3}{2}. If y(1)=α(2+e−2)y(1)=\alpha(2+e^{-2}), then α\alpha is equal to:

Options

  1. A138\dfrac{13}{8}
  2. B613\dfrac{6}{13}
  3. C1213\dfrac{12}{13}
  4. D1312\dfrac{13}{12}

Correct answer

D. 1312\dfrac{13}{12}

Step-by-step solution

The given differential equation is a linear differential equation of the form dydx+P(x)y=Q(x)\dfrac{dy}{dx} + P(x)y = Q(x), where

P(x)=6x2+(3x2+2x3+4)e−2x(x3+2)(2+e−2x)P(x) = \dfrac{6x^2 + (3x^2 + 2x^3 + 4)e^{-2x}}{(x^3+2)(2+e^{-2x})} and Q(x)=2+e−2xQ(x) = 2 + e^{-2x}.

We can rewrite P(x)P(x) as:

P(x)=3x2(2+e−2x)+2e−2x(x3+2)(x3+2)(2+e−2x)=3x2x3+2+2e−2x2+e−2xP(x) = \dfrac{3x^2(2+e^{-2x}) + 2e^{-2x}(x^3+2)}{(x^3+2)(2+e^{-2x})} = \dfrac{3x^2}{x^3+2} + \dfrac{2e^{-2x}}{2+e^{-2x}}

The integrating factor (IF) is given by:

IF=e∫P(x)dx=e∫(3x2x3+2+2e−2x2+e−2x)dxIF = e^{\int P(x) dx} = e^{\int \left( \dfrac{3x^2}{x^3+2} + \dfrac{2e^{-2x}}{2+e^{-2x}} \right) dx}

IF=eln⁡(x3+2)−ln⁡(2+e−2x)=x3+22+e−2xIF = e^{\ln(x^3+2) - \ln(2+e^{-2x})} = \dfrac{x^3+2}{2+e^{-2x}}

The general solution of the differential equation is:

y⋅(IF)=∫Q(x)⋅(IF)dx+Cy \cdot (IF) = \int Q(x) \cdot (IF) dx + C

Substituting the values, we get:

y(x3+22+e−2x)=∫(2+e−2x)(x3+22+e−2x)dx+Cy \left( \dfrac{x^3+2}{2+e^{-2x}} \right) = \int (2+e^{-2x}) \left( \dfrac{x^3+2}{2+e^{-2x}} \right) dx + C

y(x3+22+e−2x)=∫(x3+2)dx+Cy \left( \dfrac{x^3+2}{2+e^{-2x}} \right) = \int (x^3+2) dx + C

y(x3+22+e−2x)=x44+2x+Cy \left( \dfrac{x^3+2}{2+e^{-2x}} \right) = \dfrac{x^4}{4} + 2x + C

Given y(0)=32y(0) = \dfrac{3}{2}, substituting x=0x = 0:

32(0+22+e0)=0+0+C\dfrac{3}{2} \left( \dfrac{0+2}{2+e^0} \right) = 0 + 0 + C

32(23)=C⇒C=1\dfrac{3}{2} \left( \dfrac{2}{3} \right) = C \Rightarrow C = 1

Thus, the particular solution is:

y(x3+22+e−2x)=x44+2x+1y \left( \dfrac{x^3+2}{2+e^{-2x}} \right) = \dfrac{x^4}{4} + 2x + 1

To find y(1)y(1), substitute x=1x = 1:

y(1)(1+22+e−2)=14+2+1y(1) \left( \dfrac{1+2}{2+e^{-2}} \right) = \dfrac{1}{4} + 2 + 1

y(1)(32+e−2)=134y(1) \left( \dfrac{3}{2+e^{-2}} \right) = \dfrac{13}{4}

y(1)=1312(2+e−2)y(1) = \dfrac{13}{12}(2+e^{-2})

Comparing this with y(1)=α(2+e−2)y(1) = \alpha(2+e^{-2}), we get:

α=1312\alpha = \dfrac{13}{12}
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