Manipal Engineering Manipal Engineering Solved Paper-2008

  • question_answer
    The solution of the equation                 \[y-x\frac{dy}{dx}=a\left( {{y}^{2}}+\frac{dy}{dx} \right)\]

    A) \[y=c(x+a)(1-ay)\]

    B) \[y=c(x+a)(1+ay)\]

    C) \[y=c(x-a)(1+ay)\]

    D)  None of the above

    Correct Answer: A

    Solution :

    Given,                 \[y-x\frac{dy}{dx}=a\left( {{y}^{2}}+\frac{dy}{dx} \right)\] \[\Rightarrow \]               \[\frac{dy}{dx}(a+x)=y-a{{y}^{2}}\] \[\Rightarrow \]               \[\int{\frac{dy}{y(1-ay)}}=\int{\frac{dx}{a+x}}\] \[\Rightarrow \]               \[\int{\left( \frac{1}{y}+\frac{a}{1-ay} \right)}dy=\int{\frac{dx}{a+x}}\] \[\Rightarrow \]               \[\log y-\log (1-ay)=\log (a+x)+\log c\] \[\Rightarrow \]               \[\log y=\log (1-ay)(a+x)c\] \[\Rightarrow \]               \[y=c(1-ay)(a+x)\]


You need to login to perform this action.
You will be redirected in 3 sec spinner