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7th Class Mathematics Algebraic Expressions Question Bank Algebraic Expressions

  • question_answer
    If \[\left( a-\frac{1}{a} \right)=7,\] then the value \[{{a}^{2}}+\frac{1}{{{a}^{2}}}\] is:

    A)  50

    B)  51

    C)  49

    D)  47

    Correct Answer: B

    Solution :

    \[{{\left( a-\frac{1}{a} \right)}^{2}}={{a}^{2}}-2+\frac{1}{{{a}^{2}}}=49\] \[\Rightarrow {{a}^{2}}+\frac{1}{{{a}^{2}}}=49+2=51\]


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