The roots of the polynomial are:
\[
\boxed{r_1 = -7, \quad r_2 = 2.25, \quad r_3 = 8.6989 \times 10^{-16} + 2.2361i, \quad r_4 = 8.6989 \times 10^{-16} - 2.2361i}.
\]
The polynomial can be expressed as:
\[
f(x) = -4(x + 7)(x - 2.25)\left( (x - 8.6989 \times 10^{-16})^2 + (2.2361)^2 \right).
\]