A) If this cubic function has a turning point at (a, 0), that suggests to me that a is a repeating root and has an even multiplicity. (b, 0) is the other root, and since this is cubic, a has a multiplicity of 2, so this polynomial would be
(Normally, I would use the variable a in front instead of d, but a is already used as one of the roots.)
The y-intercept is , or :
d = 1, so the leading coefficient of this cubic is 1:
EDIT: Cleaned this up because I can't read.