12a^2-16a+48
\(12a^2-16a+48 = 12 \cdot \left [~ \left( a-\frac23 \right) - \frac{ 2^{2.5} } {3} i ~\right] \left [~ \left( a-\frac23 \right) + \frac{ 2^{2.5} } {3} i ~\right] \)
12a^2-16a+48=4[3a^2-4a+12]
