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The particular solution of the differential equation dydx=ex2/2+xy\frac{dy}{dx} = e^{x^2/2} + xy, when x=0x = 0, y=1y = 1, is

Solution

✅ Correct Option: 2

Rearranging the given equation into standard linear form:

dydx−xy=ex2/2\dfrac{dy}{dx} - xy = e^{x^2/2}

This is a first-order linear differential equation of the form dydx+P(x) y=Q(x)\dfrac{dy}{dx} + P(x)\,y = Q(x), where P(x)=−xP(x) = -x and Q(x)=ex2/2Q(x) = e^{x^2/2}.


Finding the Integrating Factor:

I.F.=e∫P(x) dx=e∫−x dx=e−x2/2\text{I.F.} = e^{\int P(x)\,dx} = e^{\int -x\,dx} = e^{-x^2/2}


Using the solution formula y×I.F.=∫Q(x)×I.F. dx+Cy \times \text{I.F.} = \int Q(x) \times \text{I.F.}\,dx + C, we get:

y⋅e−x2/2=∫ex2/2⋅e−x2/2 dx+Cy \cdot e^{-x^2/2} = \int e^{x^2/2} \cdot e^{-x^2/2}\,dx + C

Since ex2/2⋅e−x2/2=e0=1e^{x^2/2} \cdot e^{-x^2/2} = e^0 = 1, this simplifies to:

y⋅e−x2/2=∫1 dx+Cy \cdot e^{-x^2/2} = \int 1\,dx + C

y⋅e−x2/2=x+Cy \cdot e^{-x^2/2} = x + C

Multiplying both sides by ex2/2e^{x^2/2}:

y=(x+C) ex2/2y = (x + C)\,e^{x^2/2}

This is the general solution.


Applying the initial condition y(0)=1y(0) = 1:

1=(0+C) e01 = (0 + C)\,e^{0}

C=1C = 1


The particular solution is:

y=(x+1) ex2/2\boxed{y = (x + 1)\,e^{x^2/2}}

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