[tex]\bf \left.\qquad \qquad \right.\textit{negative exponents}\\\\
a^{-{ n}} \implies \cfrac{1}{a^{ n}}
\qquad \qquad
\cfrac{1}{a^{ n}}\implies a^{-{ n}}
\qquad \qquad
a^{{{ n}}}\implies \cfrac{1}{a^{-{{ n}}}}
\\\\
-------------------------------\\\\[/tex]
[tex]\bf \cfrac{14a^8y^3-7a^4y^5+28a^{12}y^2}{7a^4y}\impliedby
\begin{array}{llll}
\textit{let us first, distribute}\\
the~denominator
\end{array}
\\\\\\
\cfrac{14a^8y^3}{7a^4y}-\cfrac{7a^4y^5}{7a^4y}+\cfrac{28a^{12}y^2}{7a^4y}
\\\\\\
\cfrac{14}{7}a^8a^{-4}y^{-1} y^3-\cfrac{7}{7}a^4a^{-4}y^{-1} y^5+\cfrac{28}{7}a^{12}a^{-4}y^{-1} y^2
\\\\\\
2a^{8-4}y^{-1+3}-1a^{4-4}y^{-1+5}+4a^{12-4}y^{-1+2}
\\\\\\
2a^4y^2-1\cdot 1y^4+4a^8y\implies 2a^4y^2-y^4+4a^8y[/tex]
