JEE Main & Advanced AIEEE Solved Paper-2003

  • question_answer
    The number of the real solutions of the equation \[{{x}^{2}}-3\left| x \right|+2=0\] is

    A) 2                             

    B) 4             

    C) 1                             

    D) 3

    Correct Answer: B

    Solution :

    \[{{x}^{2}}-3\left| x \right|+2=0\] lf \[x>0\], then \[\left| x \right|=x\] \[\therefore \]      \[{{x}^{2}}-2x-x+2=0\] \[\Rightarrow \]   \[{{x}^{2}}-2x-x+2=0\] \[\Rightarrow \]   \[x(x-2)-1\,(x-2)=0\] \[\Rightarrow \]   \[(x-1)\,(x-2)=0\] \[\Rightarrow \]   \[x=1,2\] lf\[x<0\], then \[\left| x \right|=-x\] \[\therefore \]      \[{{x}^{2}}+3x+2=0\] \[\Rightarrow \]   \[{{x}^{2}}+2x+x+2=0\] \[\Rightarrow \]   \[x(x+2)+1(x+2)=0\] \[\Rightarrow \]   \[(x+1)\,(x+2)=0\] \[\Rightarrow \]                                   \[x=-1,-2\] Hence, four solutions are possible.


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