For any constant c, define the function fc with the formula fc(x) = x^3 + 2x^2 +cx

A) Graph y=fc(x) for these values of the parameter c: c = -1, 0, 1, 2, 3, 4. What are the similarities and differences among the graphs, and how do the graphs change as the parameter increases?

B) For what values of the parameter c will fc have one local maximum and one local minimum? Use Calculus. As c increases, what happens to the distance between the local maximum and the local minimum?

C) For what values of the parameter c will fc have no local maximum or local minimum? Use calculus.

D) Are there any values of the parameter c for which fc will have exactly one horizontal tangent line?