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The integrating factor of the differential equation (xlogex)dydx+y=2logex(x log_e x)\frac{dy}{dx} + y = 2log_e x is

Solution

✅ Correct Option: 1

To find the integrating factor, the differential equation must be in standard form:

dydx+P(x)⋅y=Q(x)\frac{dy}{dx} + P(x) \cdot y = Q(x)

The integrating factor is I.F.=e∫P(x)dxI.F. = e^{\int P(x)dx}


Given equation:

(xlog⁡ex)dydx+y=2log⁡ex(x \log_e x)\frac{dy}{dx} + y = 2\log_e x

Dividing by (xlog⁡ex)(x \log_e x):

dydx+yxlog⁡ex=2log⁡exxlog⁡ex\frac{dy}{dx} + \frac{y}{x \log_e x} = \frac{2\log_e x}{x \log_e x}

dydx+1xlog⁡ex⋅y=2x\frac{dy}{dx} + \frac{1}{x \log_e x} \cdot y = \frac{2}{x}

Therefore, P(x)=1xlog⁡exP(x) = \frac{1}{x \log_e x}


The integrating factor is:

I.F.=e∫P(x)dxI.F. = e^{\int P(x)dx}

I.F.=e∫1xlog⁡exdxI.F. = e^{\int \frac{1}{x \log_e x}dx}

To solve ∫1xlog⁡exdx\int \frac{1}{x \log_e x}dx, let u=log⁡exu = \log_e x

Then dudx=1x\frac{du}{dx} = \frac{1}{x}, so du=1xdxdu = \frac{1}{x}dx

∫1xlog⁡exdx=∫1udu\int \frac{1}{x \log_e x}dx = \int \frac{1}{u}du

=log⁡eu= \log_e u

=log⁡e(log⁡ex)= \log_e(\log_e x)


I.F.=elog⁡e(log⁡ex)I.F. = e^{\log_e(\log_e x)}

I.F.=log⁡exI.F. = \log_e x

Therefore, the integrating factor is log⁡ex\log_e x.

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