7th Class Mathematics Exponents and Power Question Bank Exponents and Power

  • question_answer
    Solve \[{{81}^{2x}}={{\left( 729 \right)}^{2}}\]

    A) \[x=\frac{3}{4}\]                      

    B) \[x=\frac{2}{3}\]

    C) \[x=\frac{5}{6}\]                      

    D) \[x=\frac{3}{2}\]

    Correct Answer: D

    Solution :

    (d) \[{{\left( {{9}^{2}} \right)}^{2x}}={{\left( {{9}^{3}} \right)}^{2}}\] \[\Rightarrow {{9}^{4x}}={{9}^{6}}\Rightarrow 4x=6\Rightarrow x=\frac{3}{2}\]


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