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8th Class Mathematics Algebraic Expressions Question Bank Algebraic Expressions & Identities

  • question_answer
    If \[{{\mathbf{x}}^{\mathbf{2}}}+\frac{1}{{{\mathbf{x}}^{\mathbf{2}}}}=\mathbf{7}\], find the value of \[\left( x+\frac{1}{x} \right)\]

    A)  6                                

    B)  9               

    C)  3       

    D)  4

    Correct Answer: C

    Solution :

    (c) \[{{x}^{2}}+\frac{1}{{{x}^{2}}}=7\] \[\Rightarrow {{x}^{2}}+\frac{1}{{{x}^{2}}}+2=9\]  \[\Rightarrow {{\left( x+\frac{1}{x} \right)}^{2}}=9\] \[\Rightarrow x+\frac{1}{x}=3.\]


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