9th Class Mathematics Number System and its Operations Question Bank Number Systems

  • question_answer
    The ascending order of the surds \[\sqrt[3]{2},\sqrt[6]{3},\sqrt[9]{4},\] is ____.

    A) \[\sqrt[9]{4},\sqrt[6]{3},\sqrt[3]{2}\]                    

    B) \[\sqrt[9]{4},\sqrt[3]{2},\sqrt[6]{3}\]        

    C) \[\sqrt[3]{2},\sqrt[6]{3},\sqrt[9]{4}\]        

    D)        \[\sqrt[6]{3},\sqrt[9]{4},\sqrt[3]{2}\]        

    Correct Answer: A

    Solution :

    LCM of  3, 6, 9 = 18 \[\therefore \]\[\sqrt[3]{2}={{(2)}^{\frac{1}{3}\times \frac{6}{6}}}={{({{2}^{6}})}^{\frac{1}{18}}}={{(64)}^{\frac{1}{18}}}=\sqrt[18]{64}\] \[\sqrt[6]{3}={{(3)}^{\frac{1}{6}\times \frac{3}{3}}}={{({{3}^{3}})}^{\frac{1}{18}}}={{(27)}^{\frac{1}{18}}}=\sqrt[18]{27}\] \[\sqrt[9]{4}={{(4)}^{\frac{1}{9}\times \frac{2}{2}}}={{({{4}^{2}})}^{\frac{1}{18}}}={{(16)}^{\frac{1}{18}}}=\sqrt[18]{16}\] So, the order is, \[\sqrt[18]{27}<\sqrt[18]{27}<\sqrt[18]{64}\] \[\Rightarrow \]\[\sqrt[9]{4}<\sqrt[18]{27}<\sqrt[18]{64}\]


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