Chapter 4: Problem 1
Let \(\mathrm{f}(x)=x^{2}\) and \(\mathrm{g}(x+2)=(x+2)^{2} .\) Are \(\mathrm{f}\) and \(\mathrm{g}\) the same function? Explain why or why not.
Short Answer
Expert verified
No, \( f(x) \) and \( g(x) \) are not the same because \( g(x) = x^2 + 4x + 4 \), differing from \( f(x) = x^2 \).
Step by step solution
01
Understand the Function f(x)
The function \( f(x) = x^2 \) is a simple quadratic function where the output is the square of the input \( x \). This function takes any real number \( x \) and maps it to \( x^2 \).
02
Express Function g(x)
The function \( g(x+2) = (x+2)^2 \) represents a horizontal translation of \( f(x) \). We need to find \( g(x) \) in terms of \( x \). Let \( u = x + 2 \), then \( x = u - 2 \), hence \( g(x) = g(u - 2) = (u)^2 \) where \( u = x + 2 \).
03
Compare the Functions
For \( f(x) \), the output is \( x^2 \). For \( g(x) \), if \( x \) is shifted by 2 (i.e., \( g(x+2) \)), the function becomes \( (x+2)^2 = x^2 + 4x + 4 \). So, \( g(x) = x^2 + 4x + 4 \).
04
Analyze the Difference
In \( f(x) \), every input \( x \) results in \( x^2 \). In \( g(x) \), the additional terms \( 4x + 4 \) appear because of the horizontal shift. This means that \( g(x) \) is not identical to \( f(x) \).
05
Conclusion
Since \( f(x) = x^2 \) and \( g(x) = x^2 + 4x + 4 \) are different expressions, with \( g(x) \) having additional terms compared to \( f(x) \), the functions are not the same.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Quadratic Function
A quadratic function is one of the simplest forms of polynomial functions. The most basic type of quadratic function is given as \( f(x) = x^2 \). In this function, the input \( x \) is squared to get the output. Quadratic functions typically create a U-shaped graph called a parabola.
Key characteristics of a quadratic function include:
Key characteristics of a quadratic function include:
- It has one variable raised to the second power, such as \( x^2 \).
- The graph of a basic quadratic function is symmetrical about the y-axis.
- The function has a vertex, which is the lowest or highest point depending on its direction.
- The graph often crosses the x-axis at points called roots or zeros.
Function Transformation Insight
Function transformations involve altering the basic form of a function to create a new function. It is like bending, stretching, or shifting an existing graph. Transformations can change the position, size, or orientation of the graph.
Transformations include:
Transformations include:
- Vertical Translations: Moving the graph up or down without altering its shape.
- Horizontal Translations: Shifting the graph left or right.
- Reflections: Flipping the graph over a specific axis.
- Stretching and Shrinking: Altering the size of the graph by multiplying or dividing the function.
Exploring Horizontal Translation
A horizontal translation shifts a function left or right on the coordinate plane. When talking about the translation of \( f(x) = x^2 \) to \( g(x+2) = (x+2)^2 \), we can understand it as moving the graph of the parabola 2 units to the left.
Horizontal translations are noted as \( x + h \) in a function's equation. If \( h \) is positive, the shift is to the left. If \( h \) is negative, the shift is to the right. This modifies the input of the function and affects only the position, not the shape or orientation.
Horizontal translations are noted as \( x + h \) in a function's equation. If \( h \) is positive, the shift is to the left. If \( h \) is negative, the shift is to the right. This modifies the input of the function and affects only the position, not the shape or orientation.
- Example: For \( g(x) = (x+2)^2 \), \( h = 2 \) signifies the graph shifts 2 units to the left.
- This does not change the parabolic shape. Instead, it affects where the vertex of the parabola is positioned.
- In this particular case, \( g(x) \) compared with \( f(x) \) leads to different outputs, emphasizing the variables are not equivalent after the shift.