J & K CET Engineering J and K - CET Engineering Solved Paper-2010

  • question_answer
    The solution of the differential equation \[\frac{dy}{dx}=5+5x+10y+10xy\]is

    A)  \[\log \,(5+10y)=x+\frac{{{x}^{2}}}{2}+c\]

    B)  \[\frac{1}{10}\log \,(5+10y)=x+\frac{{{x}^{2}}}{2}+c\]

    C)  \[\frac{1}{5}\log \,(5+10y)=x+\frac{{{x}^{2}}}{2}+c\]

    D)  \[\frac{1}{10}\log \,(5+10y)=x+{{x}^{2}}+c\]

    Correct Answer: B

    Solution :

    Given,   differential equation is \[\frac{dy}{dx}=5+5x+10y+10xy\] \[\Rightarrow \] \[\frac{dy}{dx}=5(1+x)\,+10y\,(1+x)\] \[=(1+x)\,(5+10y)\] \[\Rightarrow \] \[\frac{dy}{5+10y}=(1+x)\,dx\] On integrating \[\Rightarrow \] \[\int{\frac{dy}{5+10y}\,=\int{(1+x)\,dx}}\] \[\Rightarrow \] \[\frac{1}{10}\,\log \,(5+10y)=x+\frac{{{x}^{2}}}{2}+c\]


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