Mark M. answered 03/15/16
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Mathematics Teacher - NCLB Highly Qualified
The parabola is the quadratic that has a maximum.
y = a(x - (-1))2 + 6 vertex form
y = a(x + 1)2 + 6 simplify
4 = a(-3 + 1)2 + 6 substitute other point
4 = 4a + 6 simplify
-2 = 4a subtract 6 from both sides
-1/2 = a divide both sides by 4
y = (-1/2)(x + 1)2 + 6