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Originally Posted by hopex123 What have you tried?
I don't understand how to deal with the -3 exponent.
Originally Posted by hopex123 I don't understand how to deal with the -3 exponent. $\displaystyle \displaystyle a^{-3} = \left(a^{-1}\right)^3 = \left(\frac{1}{a}\right)^3$
And from that, important for this problem $\displaystyle \left(\frac{a}{b}\right)^{-3}= \left(\frac{b}{a}\right)^3= \frac{b^3}{a^3}$
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