NTSE Sample Paper NTSE SAT Practice Test-8

  • question_answer
    If \[{{x}^{2}}+\frac{1}{{{x}^{2}}}=p\]then what is the value of \[\left( {{x}^{3}}+\frac{1}{{{x}^{3}}} \right)?\]

    A) \[{{p}^{\frac{3}{2}}}\]        

    B) \[\left( p+1 \right)\sqrt{p+2}\]

    C) \[\left( p-1 \right)\sqrt{p+2}\]

    D) \[\left( p+1 \right)\sqrt{p-2}\]

    Correct Answer: C

    Solution :

    [c] \[{{x}^{2}}+\frac{1}{{{x}^{2}}}=P\] \[\Rightarrow \,\,{{\left( x+\frac{1}{1} \right)}^{2}}=p+2\] \[\therefore \,\,\,\left( x+\frac{x}{x} \right)={{(p+2)}^{\frac{1}{2}}}\] \[{{x}^{3}}+\frac{1}{{{x}^{3}}}={{\left( x+\frac{1}{x} \right)}^{3}}-3\left( x+\frac{1}{x} \right)\] \[={{(p+2)}^{\frac{3}{2}}}-3{{(p+2)}^{\frac{1}{2}}}\] \[=(p-1)\sqrt{p+2}\]


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