JEE Main & Advanced Sample Paper JEE Main - Mock Test - 25

  • question_answer
    If \[\frac{dy}{dx}=xy+2x+3y+6\],then\[y(-1)-{{e}^{2}}y(-3)=\]

    A) \[{{e}^{2}}-1\]

    B) \[{{e}^{2}}+1\]

    C) \[2({{e}^{2}}-1)\]        

    D) \[-2({{e}^{2}}-1)\]

    Correct Answer: C

    Solution :

    [c] : We have, \[\frac{dy}{dx}=(x+3)(y+2)\] Take, X=x+3 and \[Y=y+2\Rightarrow \frac{dY}{Y}=XdX\] \[Y=A{{e}^{{{X}^{2}}/2}}\Rightarrow y=-2+A{{e}^{\frac{{{(x+3)}^{2}}}{2}}}\] Now, \[y(-1)=-2+A{{e}^{2}},y(-3)=-2+A\] \[\therefore \]\[y(-1)-{{e}^{2}}y(-3)=-2+2{{e}^{2}}=2({{e}^{2}}-1)\].


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