Give the domain and the range of each quadratic function whose graph is described. The vertex is and the parabola opens up.
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Quadratic Functions
Problem 49
Textbook Question
Write an equation in vertex form of the parabola that has the same shape as the graph of f(x) = 2x2 but with the given point as the vertex. (5, 3)
Verified step by step guidance1
Recall that the vertex form of a parabola is given by the equation \(y = a(x - h)^2 + k\), where \((h, k)\) is the vertex of the parabola and \(a\) determines the shape (width and direction) of the parabola.
Identify the value of \(a\) from the given function \(f(x) = 2x^2\). Here, \(a = 2\), which means the parabola opens upward and is narrower than the standard parabola \(y = x^2\).
Use the given vertex point \((5, 3)\) to substitute \(h = 5\) and \(k = 3\) into the vertex form equation, so it becomes \(y = 2(x - 5)^2 + 3\).
This new equation represents a parabola with the same shape as \(f(x) = 2x^2\) but shifted so that its vertex is at \((5, 3)\).
You can verify the correctness by expanding the vertex form and comparing it to the standard form or by plotting the graph to see the vertex at the correct point.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Vertex Form of a Quadratic Function
The vertex form of a quadratic function is expressed as f(x) = a(x - h)^2 + k, where (h, k) is the vertex of the parabola. This form makes it easy to identify the vertex and understand the graph's shape and position.
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Vertex Form
Effect of the 'a' Coefficient on Parabola Shape
The coefficient 'a' in a quadratic function affects the parabola's width and direction. If |a| > 1, the parabola is narrower; if 0 < |a| < 1, it is wider. A positive 'a' opens upward, while a negative 'a' opens downward.
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Horizontal Parabolas
Using a Given Vertex to Write the Equation
When given a vertex and the shape of a parabola, substitute the vertex coordinates (h, k) into the vertex form and use the known 'a' value to write the equation. This ensures the parabola has the correct shape and position.
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