JEE Main & Advanced Sample Paper JEE Main - Mock Test - 9

  • question_answer
    The general solution of differential equation, \[\sin 2x.\left( \frac{dy}{dx}-\sqrt{\tan x} \right)-y=0,\] is

    A) \[y\sqrt{\cot x}=\tan x+C\]        

    B) \[y=\sqrt{\cot x}\,\,(x+C)\]

    C) \[y\sqrt{tanx}=\cot x+C\text{ }\!\!~\!\!\text{ }\]

    D) \[y=\sqrt{\tan x}(x+C)\]

    Correct Answer: D

    Solution :

    [d] \[\sin 2x.\left( \frac{dy}{dx}-\sqrt{\tan x} \right)-y=0\] \[\Rightarrow \,\,\,\,\,\frac{dy}{dx}+\left( \frac{-1}{\sin 2x} \right)y=\sqrt{\tan x}\] Above is a Linear Differential Equation. \[I.F.={{e}^{-\int{\cos ec\,\,2xdx}}}={{e}^{-\frac{1}{2}\log \,\tan x}}=\sqrt{\cot x}\] Therefore, general solution is \[y\sqrt{\cot x}=\int{\sqrt{\cot x}\,\sqrt{\tan \,x\,}\,dx+C}\] or         \[y\sqrt{\cot x}=x+C\]


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