SSC Quantitative Aptitude Algebra Question Bank Elementary Algebra (I)

  • question_answer
    If \[2p+\frac{1}{p}=4,\]then the value of \[{{p}^{3}}+\frac{1}{8{{p}^{3}}}\]is

    A) 4

    B) 5

    C) 8

    D) 15

    Correct Answer: B

    Solution :

    [b] \[\left( 2p+\frac{1}{p} \right)=4\] \[\Rightarrow \]\[2\left( p+\frac{1}{2p} \right)=4\]\[\Rightarrow \]\[\left( p+\frac{1}{2p} \right)=2\] Cubing on both sides, we get \[\left( p+\frac{1}{2p} \right)=8\] \[\Rightarrow \]\[{{p}^{3}}+\frac{1}{8{{p}^{3}}}+3p\times \frac{1}{2p}\left( p+\frac{1}{2p} \right)=8\] \[\Rightarrow \]\[{{p}^{3}}+\frac{1}{8{{p}^{3}}}+\frac{3}{2}\times 2=8\] \[\Rightarrow \]\[{{p}^{3}}+\frac{1}{8{{p}^{3}}}=8-3\]\[\Rightarrow \]\[{{p}^{3}}+\frac{1}{8{{p}^{3}}}=5\]


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