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Mathematics

Evaluate:

[(35)2]2\Big[\Big(\dfrac{3}{5}\Big)^{-2}\Big]^{-2}

Exponents

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Answer

As we know, for any non-zero rational number a

an=1ana^{-n} = \dfrac{1}{a^n} and an=1ana^{n} = \dfrac{1}{a^{-n}}.

[(35)2]2=[(53)2]2=[(5×53×3)]2=(259)2=(925)2=9×925×25=81625\Big[\Big(\dfrac{3}{5}\Big)^{-2}\Big]^{-2}\\[1em] = \Big[\Big(\dfrac{5}{3}\Big)^2\Big]^{-2}\\[1em] = \Big[\Big(\dfrac{5 \times 5}{3 \times 3}\Big)\Big]^{-2}\\[1em] = \Big(\dfrac{25}{9}\Big)^{-2}\\[1em] = \Big(\dfrac{9}{25}\Big)^2\\[1em] = \dfrac{9 \times 9}{25 \times 25}\\[1em] = \dfrac{81}{625}

Hence, [(35)2]2=81625\Big[\Big(\dfrac{3}{5}\Big)^{-2}\Big]^{-2} = \dfrac{81}{625}

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