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

  • question_answer
    What is the solution of \[{{3}^{3x-5}}=\frac{1}{{{9}^{x}}}\]?

    A)  \[\frac{5}{2}\]                  

    B)         \[5\]                    

    C)  \[1\]                    

    D)         \[\frac{7}{3}\]                  

    Correct Answer: C

    Solution :

    \[{{3}^{3x-5}}=\frac{1}{{{9}^{x}}}\] \[\Rightarrow \]               \[{{3}^{3x-5}}={{3}^{-2x}}\] \[\Rightarrow \]               \[3x-5=-2x\] [When bases are equal, powers can be equated.] \[\Rightarrow \]               \[5x=5\] \[\Rightarrow \]               \[x=1\]


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