Answer:
quadratic coefficient = 

linear ... = -3
constant term = 3
Explanation:
1. given the vertex, set up the function in vertex form (a is unknown):
 y = a(x + 2)² + 6
2. Substitute (0,3) for x and y in the equation and solve to find a:
 3 = a(0+2)²+6
 3 = 4a+6
 -3 = 4a
 a = -3/4
3. Substitute -3/4 for a in step 1: 

4. Convert equation to standard form using the Order of Operations:
 
