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JEE MainMathematicsModerateDifferential equation

The solution of the differential equation
dydx=x+yx\frac{dy}{dx} = \frac{x + y}{x} satisfying the condition y

Show answer and solution
Given equation can be rewritten as
dydx−1x⋅y=1\frac{dy}{dx} - \frac{1}{x} \cdot y = 1
Now, I.F.

=e−∫1xdx=e−lnx=1x= e^{- \int\frac{1}{x}dx} = e^{\mathcal{- l}nx} = \frac{1}{x}
Required solution is

y(1x)=∫1xdx=lnx+cy(\frac{1}{x}) = \int\frac{1}{x}dx\mathcal{= l}nx + c
Since, y(1) = 1
⇒1=ln1+c⇒c=1\Rightarrow 1 = \mathcal{l}n1 + c \Rightarrow c = 1
∴\therefore y=x lxnx+xy = x\ \mathcal{l}xnx + x

Source: Grass-G / M-13 Mathematics Paper 4 Nov.docx

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