8th Class Mathematics Cubes and Cube Roots Question Bank Cubes and Cube Roots

  • question_answer
    The value of \[\sqrt[3]{\frac{{{a}^{6}}\times {{b}^{3}}\times {{c}^{21}}}{{{c}^{9}}\times {{a}^{12}}}}\] is ______.

    A)  \[\frac{-b{{c}^{3}}}{{{a}^{2}}}\]                    

    B)  \[\frac{b{{c}^{4}}}{{{a}^{2}}}\]         

    C)  \[\frac{-a{{b}^{4}}}{{{c}^{2}}}\]        

    D)         \[\frac{-b{{c}^{4}}}{{{a}^{2}}}\]

    Correct Answer: D

    Solution :

    We have, \[\sqrt[3]{\frac{-{{a}^{6}}\times {{b}^{3}}\times {{c}^{21}}}{{{c}^{9}}\times {{a}^{12}}}}=\sqrt[3]{\frac{-{{b}^{3}}\times {{c}^{12}}}{{{a}^{6}}}}\] \[={{\left( \frac{(-b)\times (-b)\times (-b)\times {{c}^{4}}\times {{c}^{4}}\times {{c}^{4}}}{{{a}^{2}}\times {{a}^{2}}\times {{a}^{2}}} \right)}^{\frac{1}{3}}}\] \[={{\left( \frac{-b\times {{c}^{4}}}{{{a}^{2}}} \right)}^{3\times \frac{1}{3}}}=\frac{-b{{c}^{4}}}{{{a}^{2}}}\]


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