JEE Main & Advanced Sample Paper JEE Main Sample Paper-39

  • question_answer
    If \[a\le 0\]then roots of \[{{x}^{2}}-2a\left| x-a \right|-3{{a}^{2}}=0\]is

    A)  \[(-1+\sqrt{6})a\]                  

    B)  \[(\sqrt{6}-1)a\]

    C)  a                                

    D)  None of these

    Correct Answer: A

    Solution :

     For \[x\ge a,\] , the equation becomes \[{{x}^{2}}-2a(x-a)-3{{a}^{2}}=0\Rightarrow x=(1+\sqrt{2})a,(1-\sqrt{2})a\]for \[x\le a,\], the equation becomes \[{{x}^{2}}-2a[(x-a)]-3{{a}^{2}}=0\Rightarrow {{x}^{2}}+2ax-5{{a}^{2}}=0\]\[\Rightarrow x=-(1+\sqrt{6})a,(-1+\sqrt{6})a\] This shows \[(-1+\sqrt{{}})\]a is one of the roots.


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