8th Class Mathematics Sample Paper Mathematics Sample Paper - 10

  • question_answer
      By what number should \[{{\left( -\frac{3}{2} \right)}^{-3}}\]  be divided so that the quotient is\[{{\left( \frac{9}{4} \right)}^{-2}}\]?

    Answer:

    Let the required number = x
    According to problem,
    \[{{\left( \frac{-3}{2} \right)}^{-3}}\div x={{\left( \frac{9}{4} \right)}^{-2}}\]
    or         \[{{\left( \frac{2}{-3} \right)}^{-3}}\div x={{\left( \frac{4}{9} \right)}^{2}}\]                                                                                                     
    or          \[\frac{8}{-27}\times {{x}^{-1}}=\frac{16}{81}\] \[\left[ \because \,\,\frac{1}{{{x}^{a}}}={{x}^{-a}} \right]\]
    or           \[{{x}^{-1}}=\frac{16}{81}\times \frac{-27}{8}\]
    or       \[{{x}^{-1}}=\frac{-2}{3}\]
    or        \[\frac{1}{x}=\frac{-2}{3}\]
    or         \[x=\frac{-3}{2}\]
    Hence,   required number \[=\frac{-3}{2}\]   


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