Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
4. Polynomial Functions
Quadratic Functions
Problem 21
Textbook Question
In Exercises 17–38, use the vertex and intercepts to sketch the graph of each quadratic function. Give the equation of the parabola's axis of symmetry. Use the graph to determine the function's domain and range. y−1=(x−3)^2
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1
Step 1: Start by rewriting the given equation in the standard form of a quadratic function. The given equation is \( y - 1 = (x - 3)^2 \). Add 1 to both sides to get \( y = (x - 3)^2 + 1 \).
Step 2: Identify the vertex of the parabola. The equation \( y = (x - 3)^2 + 1 \) is in vertex form \( y = a(x - h)^2 + k \), where \( (h, k) \) is the vertex. Here, \( h = 3 \) and \( k = 1 \), so the vertex is \( (3, 1) \).
Step 3: Determine the axis of symmetry. The axis of symmetry for a parabola in vertex form \( y = a(x - h)^2 + k \) is the vertical line \( x = h \). Therefore, the axis of symmetry is \( x = 3 \).
Step 4: Find the x-intercepts by setting \( y = 0 \) and solving for \( x \). Set \( 0 = (x - 3)^2 + 1 \) and solve for \( x \).
Step 5: Determine the domain and range of the function. Since this is a quadratic function, the domain is all real numbers. The range is determined by the vertex and the direction of the parabola. Since the parabola opens upwards, the range is \( y \geq 1 \).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Vertex of a Parabola
The vertex of a parabola is the highest or lowest point on its graph, depending on whether it opens upwards or downwards. For the quadratic function given, the vertex can be found from the equation in vertex form, y - k = a(x - h)^2, where (h, k) represents the vertex coordinates. In this case, the vertex is at (3, 1).
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Axis of Symmetry
The axis of symmetry is a vertical line that divides the parabola into two mirror-image halves. For a quadratic function in vertex form, the axis of symmetry can be determined using the x-coordinate of the vertex, which is x = h. For the given function, the axis of symmetry is x = 3.
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Domain and Range of Quadratic Functions
The domain of a quadratic function is all real numbers, as there are no restrictions on the input values. The range, however, depends on the direction the parabola opens. If it opens upwards, the range starts from the y-coordinate of the vertex to positive infinity. For the given function, since it opens upwards, the range is [1, ∞).
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