SOLUTION: I need help on understanding parabolas and how to solve them. The vertex of this parabola is at (-2,-3). When the x-value is -1, the y-value is -5. What is the coefficient of the

Algebra ->  Quadratic-relations-and-conic-sections -> SOLUTION: I need help on understanding parabolas and how to solve them. The vertex of this parabola is at (-2,-3). When the x-value is -1, the y-value is -5. What is the coefficient of the       Log On


   

Question 775143: I need help on understanding parabolas and how to solve them.
The vertex of this parabola is at (-2,-3). When the x-value is -1, the y-value is -5. What is the coefficient of the squared expression in the parabola's equation?
Answer by reviewermath(1029) About Me  (Show Source):
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Q:
The vertex of this parabola is at (-2,-3). When the x-value is -1, the y-value is -5. What is the coefficient of the squared expression in the parabola's equation?
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A:
The vertex of parabola (quadratic function) with equation y=a%28x-h%29%5E2%2Bk is (h,k).
If the vertex is (-2,-3), then h = -2, k = -3 and the quadratic function is y=a%28x%2B2%29%5E2-3. Substitute x = -1 and y = -5.
-5=a%28-1%2B2%29%5E2-3
-5 = a-3
a = -2
Therefore, y+=+-2%28x%2B2%29%5E2-3 OR y+=+-2x%5E2-8x-11
The coefficient of the squared expression is highlight%28-2%29.