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

  • question_answer
    Give the simplified form of \[\frac{{{3}^{a}}{{4}^{a-2}}{{25}^{a+1}}}{{{9}^{a-1}}{{2}^{a+1}}{{5}^{a-2}}}\].

    A)  \[{{3}^{a-2}}{{.2}^{a-5}}{{.5}^{a+4}}\]

    B)  \[{{2}^{a-5}}{{.3}^{a+2}}{{.5}^{a+4}}\]

    C)  \[{{2}^{a+5}}{{.3}^{a+2}}{{.5}^{a+4}}\]

    D)  \[{{2}^{a-5}}{{.3}^{-a22}}{{.5}^{a+4}}\]

    Correct Answer: B

    Solution :

    \[\frac{{{3}^{a}}.{{({{2}^{2}})}^{a-2}}.{{({{5}^{2}})}^{a+1}}}{{{({{3}^{2}})}^{a-1}}{{.2}^{a+1}}{{.5}^{a-2}}}\] \[=\frac{{{3}^{a}}{{.2}^{2a-4}}{{.5}^{2a+2}}}{{{3}^{2a-2}}{{.2}^{a+1}}{{.5}^{a-2}}}\] [Since\[{{({{a}^{m}})}^{n}}={{a}^{mn}}\].] \[={{3}^{a-2a+2}}{{.2}^{2a-4-a-1}}{{.5}^{2a+2-a+2}}\] Since \[\left[ \frac{{{a}^{m}}}{{{b}^{n}}}={{a}^{m-n}} \right]\] \[={{3}^{-a+2}}{{.2}^{a-5}}{{.5}^{a+4}}\] \[={{2}^{a-5}}{{.3}^{-a+2}}{{.5}^{a+4}}\]


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