Chapter 1: Problem 78
How will the graph of \(y=-(x-4)^{2}+8\) differ from the graph of \(y=-x^{2} ?\) Check by graphing both functions together.
Short Answer
Expert verified
The graph of \(y=-(x-4)^2 + 8\) is shifted right 4 units and up 8 units, compared to \( y = -x^2 \).
Step by step solution
01
Analyze the Parent Function
The parent function given is \( y = -x^2 \). This is a downward-opening parabola with its vertex at the origin \((0, 0)\).
02
Identify Transformations in the New Function
The function \( y = -(x-4)^2 + 8 \) represents a transformation of the parent function. The expression \((x-4)\) indicates a horizontal shift to the right by 4 units, and the \(+8\) indicates a vertical shift upwards by 8 units.
03
Determine the Vertex of the New Function
The vertex of the parent function \( y = -x^2 \) is \((0, 0)\). After applying the transformations, the vertex of the function \( y = -(x-4)^2 + 8 \) moves to \((4, 8)\).
04
Compare Both Graphs
Both functions are parabolas that open downwards, but the graph of \( y = -(x-4)^2 + 8 \) is shifted 4 units to the right and 8 units up compared to the graph of \( y = -x^2 \).
05
Confirm with Graphing
Graphing both functions confirms the transformations: \( y = -x^2 \) has its vertex at the origin, while \( y = -(x-4)^2 + 8 \) has its vertex at \((4, 8)\) and maintains the same downward-opening shape.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Functions
Quadratic functions are a fundamental concept in algebra and are often expressed in the form \( y = ax^2 + bx + c \). The general shape of a quadratic function’s graph is a parabola. The orientation and position of this parabola can vary, but it generally has a distinctive U-shape. The key components include:
- The a value, which affects the parabola's width and orientation (upwards if positive, downwards if negative).
- The b and c values which influence the parabola's position along the x-axis and y-axis, respectively.
Vertex Form
The vertex form of a quadratic function is particularly useful for graphing and understanding transformations. A quadratic function in vertex form is written as \( y = a(x-h)^2 + k \). This form highlights:
- The vertex \((h, k)\), which is the highest or lowest point on the graph.
- The a value, which determines the direction and width of the parabola (same as in the standard form).
Graphing Transformations
Transformations help us understand how the graph of a quadratic function changes or shifts. These transformations include horizontal and vertical shifts, which are essential for comparing graphs of similar functions. The common transformations include:
- Horizontal Shifts: Occur when we add or subtract inside the parentheses \((x-h)\). For example, \( (x - 4) \) indicates a shift to the right by 4 units.
- Vertical Shifts: Occur when adding or subtracting outside the parentheses, such as the \(+ 8\), indicating a shift upwards by 8 units.
- Reflection: Happens if the coefficient of \(x^2\) is negative, flipping the parabola downwards. Our function \( y = -(x-4)^2 + 8 \) retains this reflection from the parent function \( y = -x^2 \).