8th Class Mathematics Sample Paper Mathematics Sample Paper - 9

  • question_answer
    Find the value of x for which     \[{{\left( \frac{4}{9} \right)}^{4}}\times {{\left( \frac{4}{9} \right)}^{-7}}={{\left( \frac{4}{9} \right)}^{2x-1}}\]

    Answer:

    Since, \[{{\left( \frac{4}{9} \right)}^{4}}\times {{\left( \frac{4}{9} \right)}^{-7}}={{\left( \frac{4}{9} \right)}^{2x-1}}\]
    or  \[{{\left( \frac{4}{9} \right)}^{4+(-7)}}={{\left( \frac{4}{9} \right)}^{2x-1}}\]
    or \[{{\left( \frac{4}{3} \right)}^{-3}}={{\left( \frac{4}{9} \right)}^{2x-1}}\]
    By comparing with powers then,
    \[-~~3=2x1\]
    \[2x=-3+1\]
    or \[~2x=2\]
    or \[x=-\frac{2}{2}=-1\]
    Hence,\[x=1\]
         


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