Chapter 8: Problem 10
Describe the order of transformations of the graph of \(y=x^{2}\) represented by a. \(y=-(x+3)^{2}\) (h) b. \(y=0.5(x-2)^{2}+1\)
Short Answer
Expert verified
a. Reflection over x-axis and left 3 units; b. Vertical compression, right 2 units, and up 1 unit.
Step by step solution
01
Step 1a: Identify the base function and transformations
The base function is \( y = x^2 \). For part (a), the function is \( y = -(x+3)^2 \). This equation represents a reflection over the x-axis and a horizontal shift. The minus sign indicates a reflection, while \( (x+3) \) shows a shift to the left by 3 units.
02
Step 2a: Apply transformations to the base function for part a
Starting with \( y = x^2 \), we reflect it over the x-axis to get \( y = -x^2 \). Next, we apply a horizontal shift by replacing \( x \) with \( x+3 \), leading to the transformed equation \( y = -(x+3)^2 \).
03
Step 1b: Identify the base function and transformations for part b
For part (b), the function is \( y = 0.5(x-2)^2 + 1 \). This involves a vertical stretch/compression, a horizontal shift, and a vertical shift. The coefficient \( 0.5 \) indicates a vertical compression, \( (x-2) \) shows a shift to the right by 2 units, and the addition of 1 indicates a vertical shift upwards by 1 unit.
04
Step 2b: Apply transformations to the base function for part b
Starting with \( y = x^2 \), apply the vertical compression by multiplying \( x^2 \) by 0.5 to get \( y = 0.5x^2 \). Next, apply the horizontal shift by replacing \( x \) with \( x-2 \), giving \( y = 0.5(x-2)^2 \). Finally, apply the vertical shift by adding 1, resulting in \( y = 0.5(x-2)^2 + 1 \).
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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 mathematical expressions of the form: \[ y = ax^2 + bx + c \] where \( a \), \( b \), and \( c \) are constants, and \( a eq 0 \). The simplest form is the parent function \( y = x^2 \). When you graph a basic quadratic function, it forms a "U" shaped curve called a parabola. The point where the parabola changes direction is called the vertex, and the line through the vertex, splitting the parabola symmetrically, is known as the axis of symmetry.
- The graph of a quadratic function opens upwards if \( a > 0 \).
- If \( a < 0 \), the graph opens downwards and results in a reflection across the x-axis.
- Complex versions involve transforming the parent graph through various shifts, stretching, or compressing.
Horizontal Shift
A horizontal shift involves moving the entire graph of a function left or right on the Cartesian plane. It changes the x-coordinates of the graph while keeping the y-coordinates the same. In the context of quadratic functions, a horizontal shift is expressed as \[ y = (x - h)^2 \] where \( h \) is the number of units the graph is shifted.
- To shift the graph to the right, use \( (x - h) \).
- To shift it to the left, use \( (x + h) \).
Vertical Shift
A vertical shift adds or subtracts a constant from the function, moving the graph up or down. This transformation affects the y-values of the graph. For quadratic functions, it is shown as \[ y = x^2 + k \] where \( k \) is the number of units the graph is shifted.
- Add \( k \): shifts the graph upward by \( k \) units.
- Subtract \( k \): shifts the graph downward by \( k \) units.
Reflection
Reflecting a graph means flipping it over a given axis. In the case of quadratic functions, reflection often occurs over the x-axis. This transformation is expressed by multiplying the entire function by \(-1\). For a quadratic function, a reflection over the x-axis is represented as \[ y = -ax^2 \] This means:
- The parabola will open downwards instead of upwards.
- The vertex will remain on the same axis of symmetry, but its y-coordinate will change signs.