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

  • question_answer
    Let a and P be the roots of the equation \[{{x}^{2}}+x+1=0\]the equation whose roots are \[{{\alpha }^{19}},{{\beta }^{7}}\]is

    A)  \[{{x}^{2}}-x-1=0\]           

    B)  \[{{x}^{2}}-x+1=0\]

    C)  \[{{x}^{2}}+x-1=0\]        

    D)  \[{{x}^{2}}+x+1=0\]

    Correct Answer: D

    Solution :

     The roots of the equation x2 + x + 1 are given as \[\omega \And {{\omega }^{2}}.\]i,e. say, \[\alpha =\omega \And \beta ={{\omega }^{2}}\] \[{{\alpha }^{19}}={{\omega }^{19}}={{({{\omega }^{3}})}^{6}}\omega =\omega ;{{B}^{7}}=\] \[{{({{\omega }^{2}})}^{7=}}{{\omega }^{14}}={{({{\omega }^{3}})}^{4}}{{\omega }^{2}}={{\omega }^{2}}\] Hence the equation is \[{{x}^{2}}+x+1=0\]


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