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The general solution of the differential equation, $$\sin 2x\left(\frac{dy}{dx} - \sqrt{\tan x}\right) - y = 0$$, is:
The given differential equation is:
$$\sin 2x\left(\frac{dy}{dx} - \sqrt{\tan x}\right) - y = 0$$
First, expand the equation:
$$\sin 2x \cdot \frac{dy}{dx} - \sin 2x \cdot \sqrt{\tan x} - y = 0$$
Recall that $$\sin 2x = 2 \sin x \cos x$$, so substitute:
$$2 \sin x \cos x \cdot \frac{dy}{dx} - 2 \sin x \cos x \cdot \sqrt{\tan x} - y = 0$$
Rearrange the terms to isolate the derivative:
$$2 \sin x \cos x \cdot \frac{dy}{dx} - y = 2 \sin x \cos x \cdot \sqrt{\tan x}$$
Divide both sides by $$\sin x \cos x$$:
$$\frac{2 \sin x \cos x \cdot \frac{dy}{dx}}{\sin x \cos x} - \frac{y}{\sin x \cos x} = \frac{2 \sin x \cos x \cdot \sqrt{\tan x}}{\sin x \cos x}$$
Simplify:
$$2 \frac{dy}{dx} - \frac{y}{\sin x \cos x} = 2 \sqrt{\tan x}$$
Note that $$\frac{1}{\sin x \cos x} = \frac{2}{\sin 2x}$$, so:
$$2 \frac{dy}{dx} - 2 \frac{y}{\sin 2x} = 2 \sqrt{\tan x}$$
Divide both sides by 2:
$$\frac{dy}{dx} - \frac{y}{\sin 2x} = \sqrt{\tan x}$$
This is a linear differential equation of the form $$\frac{dy}{dx} + P(x) y = Q(x)$$, where $$P(x) = -\frac{1}{\sin 2x}$$ and $$Q(x) = \sqrt{\tan x}$$.
The integrating factor (I.F.) is $$e^{\int P(x) dx} = e^{\int -\frac{1}{\sin 2x} dx}$$.
Compute $$\int -\frac{1}{\sin 2x} dx$$. Since $$\frac{1}{\sin 2x} = \csc 2x$$, we have $$\int -\csc 2x dx$$.
Let $$\theta = 2x$$, so $$d\theta = 2 dx$$ and $$dx = \frac{d\theta}{2}$$:
$$\int -\csc \theta \cdot \frac{d\theta}{2} = -\frac{1}{2} \int \csc \theta d\theta$$
The integral of $$\csc \theta$$ is $$\ln |\csc \theta - \cot \theta| + C$$, so:
$$-\frac{1}{2} \int \csc \theta d\theta = -\frac{1}{2} \ln |\csc \theta - \cot \theta| + C$$
Substitute back $$\theta = 2x$$:
$$-\frac{1}{2} \ln |\csc 2x - \cot 2x| + C$$
Simplify $$\csc 2x - \cot 2x$$:
$$\csc 2x - \cot 2x = \frac{1}{\sin 2x} - \frac{\cos 2x}{\sin 2x} = \frac{1 - \cos 2x}{\sin 2x}$$
Use identities $$1 - \cos 2x = 2 \sin^2 x$$ and $$\sin 2x = 2 \sin x \cos x$$:
$$\frac{2 \sin^2 x}{2 \sin x \cos x} = \frac{\sin x}{\cos x} = \tan x$$
Thus:
$$\int -\frac{1}{\sin 2x} dx = -\frac{1}{2} \ln |\tan x| + C$$
The integrating factor is:
$$I.F. = e^{-\frac{1}{2} \ln |\tan x|} = e^{\ln |\tan x|^{-1/2}} = |\tan x|^{-1/2}$$
Since $$\sqrt{\tan x}$$ is in the equation, we consider $$\tan x \gt 0$$, so drop the absolute value:
$$I.F. = (\tan x)^{-1/2} = \frac{1}{\sqrt{\tan x}} = \sqrt{\cot x}$$
The solution of the linear differential equation is:
$$y \cdot (I.F.) = \int Q(x) \cdot (I.F.) dx + C$$
$$y \sqrt{\cot x} = \int \sqrt{\tan x} \cdot \sqrt{\cot x} dx + C$$
Simplify the integrand:
$$\sqrt{\tan x} \cdot \sqrt{\cot x} = \sqrt{\tan x \cdot \cot x} = \sqrt{1} = 1$$
Thus:
$$y \sqrt{\cot x} = \int 1 dx + C = x + C$$
Comparing with the options:
A. $$y\sqrt{\tan x} = x + c$$
B. $$y\sqrt{\cot x} = \tan x + c$$
C. $$y\sqrt{\tan x} = \cot x + c$$
D. $$y\sqrt{\cot x} = x + c$$
Hence, the correct answer is Option D.
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