Answer
$\displaystyle \frac{49}{c^{6}d^{4}}$
Work Step by Step
$[\displaystyle \frac{c^{3}}{7d^{-2}}]^{-2}$ =......... $(\displaystyle \frac{a}{b})^{m}=\frac{a^{m}}{b^{m}}$
$=\displaystyle \frac{(c^{3})^{-2}}{(7d^{-2})^{-2}}$ =......... $(ab)^{m}=a^{m}b^{m}$
$=\displaystyle \frac{(c^{3})^{-2}}{7^{-2}(d^{-2})^{-2}}$=......... $(a^{m})^{n}=a^{mn}$
$=\displaystyle \frac{c^{(3)(-2)}}{7^{-2}d^{(-2)(-2)}}$
$=\displaystyle \frac{c^{-6}}{7^{-2}d^{4}}$=.........$\displaystyle \frac{1}{a^{n}}=a^{-n}$
$=\displaystyle \frac{7^{2}}{c^{6}d^{4}}$
$=\displaystyle \frac{49}{c^{6}d^{4}}$
