3 c - 16*c
c^3 - 16*c
/ 2\ c*\-16 + c /
c*(-16 + c^2)
1*(c + 4)*(c + 0)*(c - 4)
((1*(c + 4))*(c + 0))*(c - 4)
c^3 - 16.0*c
c*(-4 + c)*(4 + c)