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

  • question_answer
    By what number \[{{\left( \frac{4}{5} \right)}^{-5}}\]  must be multiplied so that the result is\[\frac{16}{9}\]?

    A)  \[\frac{3}{2}\]                         

    B)  \[{{\left( \frac{4}{3} \right)}^{7}}\]

    C)  \[\frac{1}{3}\]                                     

    D)  \[\frac{1}{2}\]

    Correct Answer: B

    Solution :

    (b) Let no be \[{{\left( \frac{4}{3} \right)}^{a}}\] Then, \[{{\left( \frac{4}{3} \right)}^{-5}}\times {{\left( \frac{4}{3} \right)}^{a}}=\frac{16}{9}or{{\left( \frac{4}{3} \right)}^{2}}\] \[\Rightarrow {{\left( \frac{4}{3} \right)}^{(-5+a)}}={{\left( \frac{4}{3} \right)}^{2}}\] \[\Rightarrow a-5=2\Rightarrow a=7\] \[={{\left( \frac{4}{3} \right)}^{7}}\]. Mind of Mathematician: See the ingenuity, as we have not started by saying that let the no. be ?a?. Rather, we have started by saying, ?Let the no be \[{{\left( \frac{4}{3} \right)}^{n}}\].


You need to login to perform this action.
You will be redirected in 3 sec spinner