SSC Sample Paper SSC CHSL (10+2) Sample Test Paper-5

  • question_answer
    If \[x+\frac{1}{x}=-2\] then the value of \[{{x}^{2n+1}}+\frac{1}{{{x}^{2n+1}}}\] where \[n\] is a positive integer, is

    A) \[0\]                             

    B) \[2\]

    C) \[-2\]      

    D)        \[-5\]

    Correct Answer: C

    Solution :

                \[x+\frac{1}{x}=-2\]                             ? (i) \[\therefore \]      \[{{\left( x-\frac{1}{x} \right)}^{2}}={{\left( x+\frac{1}{x} \right)}^{2}}-4\]             \[={{(-2)}^{2}}-4=0\] \[\Rightarrow \]   \[x-\frac{1}{x}=0\]                                ? (ii) Solving equations (i) and (ii), we have \[\therefore \]      \[x=-1\] \[\therefore \]      \[{{x}^{2n+1}}+\frac{1}{{{x}^{2n+1}}}\]             \[={{(-1)}^{2n+1}}+\frac{1}{{{(-1)}^{2n+1}}}\]             \[=-1-1=-2\]


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