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

  • question_answer
    If \[{{8}^{x-1}}={{2}^{x+3}},\]then \[x\] is

    A)  2                                

    B)  1            

    C)  0                                

    D)  3

    Correct Answer: D

    Solution :

    (d) \[{{8}^{x-1}}={{2}^{x+3}}\Rightarrow {{\left( {{2}^{3}} \right)}^{x-1}}={{2}^{x+3}}\Rightarrow {{2}^{3x-3}}={{2}^{x-3}}\] \[\Rightarrow \]\[3x-3=x+3\Rightarrow 2x=6\Rightarrow x=3\]


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