Understanding Parabola Translations in Quadratic Functions
Learn how to apply vertical and horizontal translations to parabolas, shifting their position without changing shape. Explore vertex form and quadratic functions modeling.
Understanding Parabola Translations in Quadratic Functions
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Presentation Transcript
Section 8.2 • Parabolas and Modeling
Objectives Vertical and Horizontal Translations Vertex Form Modeling with Quadratic Functions (Optional)
Vertical and Horizontal Translations • The graph of y = x2 is a parabola opening upward with vertex (0, 0). • All three graphs have the same shape. • y = x2 • y = x2 + 1 shifted upward 1 unit • y = x2 – 2 shifted downward 2 units • Such shifts are called translations because they do not change the shape of the graph only its position
Vertical and Horizontal Translations • The graph of y = x2 is a parabola opening upward with vertex (0, 0). • y = x2 • y = (x – 1)2 • Horizontal shift to the right 1 unit
Vertical and Horizontal Translations • The graph of y = x2 is a parabola opening upward with vertex (0, 0). • y = x2 • y = (x + 2)2 • Horizontal shift to the left 2 units
Example Sketch the graph of the equation and identify the vertex. Solution The graph is similar to y = x2 except it has been translated 3 units down. The vertex is (0, 3).
Example Sketch the graph of the equation and identify the vertex. Solution The graph is similar to y = x2 except it has been translated left 4 units. The vertex is (4, 0).
Example Sketch the graph of the equation and identify the vertex. Solution The graph is similar to y = x2 except it has been translated down 2 units and right 1 unit. The vertex is (1, 2).
Example Compare the graph of y = f(x) to the graph of y = x2. Then sketch a graph of y = f(x) and y = x2 in the same xy-plane. Solution The graph is translated to the right 2 units and upward 3 units. The vertex for f(x) is (2, 3) and the vertex of y = x2 is (0, 0). The graph opens upward and is wider.
Example Write the vertex form of the parabola with a = 3 and vertex (2, 1). Then express the equation in the form y = ax2 + bx + c. Solution The vertex form of the parabola is where the vertex is (h, k). a = 3, h = 2 and k = 1 To write the equation in y = ax2 + bx + c, do the following:
Example Write each equation in vertex form. Identify the vertex. a. b. Solution a. Because , add and subtract 16 on the right.
Example (cont) b. This equation is slightly different because the leading coefficient is 2 rather than 1. Start by factoring 2 from the first two terms on the right side.