KVPY Sample Paper KVPY Stream-SX Model Paper-31

  • question_answer
    If \[|\sqrt{x}-2|+\sqrt{x}\left( \sqrt{x}-4 \right)=2,\] then find the sum of roots of equation-

    A) 12

    B) 8

    C) 4

    D) 16

    Correct Answer: D

    Solution :

    \[|\sqrt{x}-2|+x-4\sqrt{x}=2\]\[\Rightarrow \] \[|\sqrt{x}-2|+{{\left( \sqrt{x} \right)}^{2}}-4\sqrt{x}+4=6\]\[\Rightarrow \] \[{{\left( \sqrt{x}-2 \right)}^{2}}+|\sqrt{x}-2|=6\]
    Let        \[|\sqrt{x}-2|=t\]\[\Rightarrow \]  \[{{t}^{2}}+t-6=0\]\[\Rightarrow \]        \[(t+3)(t-2)=0\]\[\Rightarrow \]\[t=2\]or \[t=-3\]
    but \[t=-3\] not possible,
    \[|\sqrt{x}-2|=2\]\[\Rightarrow \] \[\sqrt{x}-2=\pm 2\]\[\Rightarrow \]          \[\sqrt{x}=0\]or\[\sqrt{x}=4\]\[\Rightarrow \]\[x=0\]or\[x=16.\]


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