The 3D printer prints a solid \( 5 \) centimetre cube in \( 2 \) hours. The printer can print the cube with the maximum edge length of \( 20\,\mathrm{cm} \). Suppose the printing time is directly proportional to the cube volume. Choose the function that describes the dependence of the number \( n \) of cubes printed in \( 1 \) day on the printed cube edge length \( a \), which is specified in centimetres. Neglect time needed for using the printer.
We are given three quadratic functions:
\[ \begin{aligned}
f_1(x)&=ax^2+2ax+a-3, \\
f_2(x)&=a(x-1)^2+2, \\
f_3(x)&=ax^2,
\end{aligned} \]
where \( a\in(-\infty;0) \). If possible, determine which of the given functions has the highest output value for \( x = 0.5 \).