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The general solution of the differential equation dydx−yx+cosec(yx)=0\frac{dy}{dx}-\frac{y}{x}+\text{cosec}\left(\frac{y}{x}\right)=0 is

(Consider log⁡x=log⁡ex\log x=\log_e x)

Solution

✅ Correct Option: 3

This is homogeneous, so put y=vxy=vx: v+xdvdx=v−cosec vv+x\frac{dv}{dx}=v-\text{cosec}\,v, giving sin⁡v dv=−dxx\sin v\,dv=-\frac{dx}{x}. Integrating, −cos⁡v=−log⁡x+C′-\cos v=-\log x+C', i.e. cos⁡(yx)=log⁡x+C\cos\left(\frac{y}{x}\right)=\log x+C.

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