CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2005

  • question_answer
    The general solution of the differential equation \[(2x-y+1)\,dx+(2y-x+1)\,\,dy=0\] is:

    A)  \[{{x}^{2}}+{{y}^{2}}+xy-x+y=c\]

    B)  \[{{x}^{2}}+{{y}^{2}}-xy+x+y=c\]

    C)  \[{{x}^{2}}-{{y}^{2}}+2xy-x+y=c\]

    D)  \[{{x}^{2}}-{{y}^{2}}-2xy+x-y=c\]

    Correct Answer: B

    Solution :

    Given differential equation is \[(2x-y+1)\,dx+(2y-x+1)\,dy=0\] \[\Rightarrow \,\,2x\,dx+2y\,dy-(y\,dx+x\,dy)\]                                                 \[+\,dx+dy=0\] \[\Rightarrow \,\,\,(2x\,dx+2y\,dy)-d\,\,(xy)+dx+dy=0\] On integrating both sides, we get \[{{x}^{2}}+{{y}^{2}}-xy+x+y=c\]


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