Answer
$p^{-7/4} \left( p-2 \right)$
Work Step by Step
Factoring the given factor, $
p^{-7/4}
,$ then the given expression, $
p^{-3/4}-2p^{-7/4}
,$ is equivalent to
\begin{array}{l}\require{cancel}
p^{-7/4} \left( \dfrac{p^{-3/4}}{p^{-7/4}}-\dfrac{2p^{-7/4}}{p^{-7/4}} \right)
\\\\=
p^{-7/4} \left( p^{-\frac{3}{4}-\left(-\frac{7}{4}\right)}-2p^{-\frac{7}{4}-\left(-\frac{7}{4}\right)} \right)
\\\\=
p^{-7/4} \left( p^{-\frac{3}{4}+\frac{7}{4}}-2p^{-\frac{7}{4}+\frac{7}{4}} \right)
\\\\=
p^{-7/4} \left( p^{\frac{4}{4}}-2p^{0} \right)
\\\\=
p^{-7/4} \left( p^{1}-2(1) \right)
\\\\=
p^{-7/4} \left( p-2 \right)
.\end{array}
