
\begin{enumerate}
\item $\begin{aligned}[t]
f(x) & =-5(x+3)(4-2x)\\
& = -5(4x-2x^2+12-6x)\\
& = -5(-2x^2-2x+12)\\
\Aboxed{f(x)&=10x^2+10x-60}
\end{aligned}$

\item $\begin{aligned}[t]
f(x)&=2(x+3)^2-7\\
& = 2(x^2+6x+9)-7\\
& = 2x^2+12x+18-7\\
\Aboxed{f(x) & =2x^2+12x+11}
\end{aligned}$

\item $\begin{aligned}[t]
f(x)&=\dfrac{1}{2}(x-6)^2+\dfrac{3}{2}\\
&=\dfrac{1}{2}(x^2-12x+36)+\dfrac{3}{2}\\
& = \dfrac{1}{2}x^2-6x+18+\dfrac{3}{2}\\
\Aboxed{f(x) & = \dfrac{1}{2}x^2-6x+\dfrac{39}{2}}
\end{aligned}$

\item $\begin{aligned}[t]
f(x)&=3(x-8)(x+1)\\
& = 3(x^2+x-8x-8)\\
& = 3(x^2-7x-8)\\
\Aboxed{f(x) & = 3x^2-21x-24}
\end{aligned}$
\end{enumerate}
