Chapter 1: Problem 21
Graph the function and its parent function. Then describe the transformation. \(f(x)=2 x^2\)
Short Answer
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The given function \(f(x)=2 x^2\) is a vertical stretch of its parent function \(g(x) = x^2\) by a factor of 2. The graph of \(f(x)=2 x^2\) is narrower compared to \(g(x) = x^2\).
Step by step solution
01
Identify the Parent Function
Start by identifying the parent function. In this case, our parent function is \(g(x) = x^2\). This is a basic quadratic function, which looks like a U-shape or a parabola.
02
Understand Transformations
The next step is to understand what the given function \(f(x)=2 x^2\) tells us about transformations. The 2 in this function 'stretches' it vertically by a factor of 2.
03
Graph the Parent Function
Using graph paper or graphing software, graph the parent function \(g(x) = x^2\). Note that it passes through the point (0,0) - the origin, and the curve is symmetrical about the y-axis.
04
Graph the Given Function
Next, graph the given function \(f(x)=2 x^2\).Since there's a vertical stretch, the curve of the graph will be narrower than that of the parent function.
05
Describe Transformations
Finally, describe the transformation from \(g(x) = x^2\) to \(f(x)=2 x^2\). The function \(f(x)=2 x^2\) is a vertical stretch of \(g(x) = x^2\) by a factor of 2.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Parabola
A parabola is a U-shaped curve that is the graph of a quadratic function. Quadratic functions are essential in algebra and take the form \( y = ax^2 + bx + c \). The parabolas can open upwards or downwards; in our example, with \( f(x) = 2x^2\), it opens upwards because the coefficient of \( x^2 \), which is 2, is positive.
- An upward-opening parabola has a lowest point known as the vertex. In the parent function \( g(x) = x^2 \), the vertex is at the origin (0,0).
- The y-axis is the line of symmetry. This means if you fold the parabola along the y-axis, both halves will match perfectly.
- The wider the parabola, the smaller the coefficient of \( x^2 \).
- The more narrow the parabola, the larger the coefficient of \( x^2 \).
Parent Function
The parent function for all quadratic functions is the simplest quadratic equation, represented by \( g(x) = x^2 \). This function forms the basis for many transformations and is crucial in understanding more complex quadratic functions.
- It forms a standard parabola that opens upwards with a vertex at the origin.
- The parent function is symmetrical about the y-axis and shows how every quadratic function evolves through modifications.
- It passes through points such as (0,0), (1,1), and (-1,1), which helps in plotting its graph accurately.
Transformation
Transformations involve altering the parent function to create a new graph through actions such as stretching, shrinking, translating, or reflecting. In the case of \( f(x) = 2x^2 \), we have a vertical stretch.
- The coefficient 2 in \( f(x) = 2x^2 \) stretches the parabola vertically by a factor of 2, making it narrower than the parent function.
- Vertical stretches affect the y-values by multiplying them, moving points away from the x-axis.
Graphing
Graphing a quadratic function involves plotting points and understanding its movements via transformations. Let's focus on sketching \( f(x) = 2x^2 \) and its parent function.
- Begin by graphing the parent function \( g(x) = x^2 \). Plot key points like (0,0), (1,1), and (-1,1).
- Once the parent parabola is drawn, apply the vertical stretch to all y-values to graph \( f(x) = 2x^2 \). This means doubling each y-value; thus, the graph appears narrower or steeper.
- Ensure symmetry is maintained about the y-axis. The vertex remains in the same position unless other different transformations are applied.