My recommendation would be to factor..
x² + 4x + 3 = 0 factor the left side into two binomials
(x + 3)(x + 1) = 0 set each of these binomials equal to zero and solve
x + 3 = 0 Implies x = -3
x + 1 = 0 implies x = -1
GCF = -c^2d^3
Factors are -c^2d^3(8c^3d^3 + 27c^2d + 24)
