Answer: Any really 
Explanation:
a) Factor: 
.. (x -h +√(-k/a)) * (x -h -√(-k/a)) 
b) Graph: 
.. It is a graph of y=x^2 with the vertex translated to (h, k) and vertically stretched by a factor of "a". 
c) Vertex and Extreme: 
.. The vertex is (h, k). It is a maximum if "a" is negative; a minimum otherwise. 
d) Solutions: 
.. The quadratic formula is based on the notion of completing the square. In vertex form, the square is already completed, so the roots are 
.. x = h ± √(-k/a)