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8th Class Mathematics Exponents and Power Question Bank Exponents and Powers

  • question_answer
    The value of x so that \[{{\left( \frac{2}{7} \right)}^{4}}.{{\left( \frac{2}{7} \right)}^{3}}={{\left( \frac{2}{7} \right)}^{4x-1}}\]   is

    A)  1                                

    B)  2   

    C)  3                                

    D)  4

    Correct Answer: B

    Solution :

    (b) \[{{\left( \frac{2}{7} \right)}^{4}}\bullet {{\left( \frac{2}{7} \right)}^{3}}={{\left( \frac{2}{7} \right)}^{4x-1}}\] \[\Rightarrow {{\left( \frac{2}{7} \right)}^{7}}={{\left( \frac{2}{7} \right)}^{4x-1}}\Rightarrow 7=4x-1\] \[\Rightarrow x=2\]


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