Answer:
D.
Step-by-step explanation:
Answer:

Step-by-step explanation:
Vertex form of a quadratic equation;

Vertex of the parabolas (h, k)
The vertex of the parabola is either the minimum or maximum of the parabola. The axis of symmetry goes through the x-coordinate of the vertex, hence h = -3. The minimum of the parabola is the y-coordinate of the vertex, so k= 7. Now substitute it into the formula;

Now substitute in the given point; ( -1, 9) and solve for a;

Hence the equation in vertex form is;

In standard form it is;

There exist an abbreviation that ALL - S - T - C where all trigonometric functions in first quandrant are positive. S, T, and C are the first letters of the trigonometric functions that are positive in quadrant 2, 3, and 4, respectively. This also means that in the same quadrant, their reciprocals are also positive. For the given above, it is in Quadrant 3 where T is positive and cosine is negative.