CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2006

  • question_answer
    If\[{{\alpha }_{1}},{{\alpha }_{2}},{{\alpha }_{3}},{{\alpha }_{4}}\]are the roots of the equation\[{{x}^{4}}+(2-\sqrt{3}){{x}^{2}}+2+\sqrt{3}=0,\]then the value of\[(1-{{\alpha }_{1}})(1-{{\alpha }_{2}})(1-{{\alpha }_{3}})(1-{{\alpha }_{4}})\]is:

    A)  1                            

    B)         4

    C)  \[2+\sqrt{3}\]                  

    D)         5

    E)  0

    Correct Answer: D

    Solution :

    \[(1-{{\alpha }_{1}})(1-{{\alpha }_{2}})(1-{{\alpha }_{3}})(1-{{\alpha }_{4}})\] \[=(1+{{\alpha }_{1}}{{\alpha }_{2}}-{{\alpha }_{1}}-{{\alpha }_{2}})(1-{{\alpha }_{3}})(1-{{\alpha }_{4}})\] \[=(1+{{\alpha }_{1}}{{\alpha }_{2}}-{{\alpha }_{1}}-{{\alpha }_{2}}-{{\alpha }_{3}}-{{\alpha }_{1}}{{\alpha }_{2}}{{\alpha }_{3}}\]                                 \[+{{\alpha }_{1}}{{\alpha }_{3}}+{{\alpha }_{2}}{{\alpha }_{3}})(1-{{\alpha }_{4}})\]  \[=1+\Sigma {{\alpha }_{1}}{{\alpha }_{2}}-\Sigma {{\alpha }_{1}}{{\alpha }_{2}}{{\alpha }_{3}}-\Sigma {{\alpha }_{1}}+{{\alpha }_{1}}{{\alpha }_{2}}{{\alpha }_{3}}{{\alpha }_{4}}\] \[=1+(2-\sqrt{3})-0-0+2+\sqrt{3}\] \[=-2\sqrt{3}+1+2+\sqrt{3}=5\]


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