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The general solution of the differential equation (1+ex)dy+yexdx=0(1 + e^x)dy + ye^x dx = 0, where y>0y > 0, is

Solution

✅ Correct Option: 3

Given: (1+ex)dy+yexdx=0(1 + e^x)dy + ye^x dx = 0 where y>0y > 0

This is a separable differential equation.

(1+ex)dy=−yexdx(1 + e^x)dy = -ye^x dx


dyy=−exdx1+ex\frac{dy}{y} = \frac{-e^x dx}{1 + e^x}


Integrating both sides:

∫dyy=∫−ex1+exdx\int \frac{dy}{y} = \int \frac{-e^x}{1 + e^x} dx

ln⁡y=−ln⁡(1+ex)+ln⁡C\ln y = -\ln(1 + e^x) + \ln C


ln⁡y+ln⁡(1+ex)=ln⁡C\ln y + \ln(1 + e^x) = \ln C

ln⁡[y(1+ex)]=ln⁡C\ln[y(1 + e^x)] = \ln C


y(1+ex)=Cy(1 + e^x) = C

Therefore, the general solution is C=y(1+ex)C = y(1 + e^x) where CC is an arbitrary constant.

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